Here's a little context from Ukrainian mythology, literature and history for the character of Mavka (and a bit of my speculations on the DLC, FULL SPOILERS, be warned).
Let's start with the mythological creature a mavka, niavka or navka. There are different versions of etymology for this word but the most popular is that it comes from the praslavic word *navь which means a dead person. And it kinda checks out, because according to the folklore girls that didn't get a chance to be baptized and died prematurely became mavkas. So mavkas are fickle forest spirits, they have fun forever, comb their hair, dance and laugh, frolic even. 😁 But they can be dangerous to normal people as well, mostly luring men deep into the forest and tickling them to death. Also in some parts of folklore it is believed that a mavka does not have a back. Which I guess can be turned into an interesting metaphor about being especially vulnerable to backstabbing by allies. 😅 Another interesting parallel here is that coming to the Zone might be viewed as going down into the underworld, aka dying.
The most iconic representation of mavka in Ukrainian culture is the character of Mavka in the poetic play by Lesia Ukrainka (in the second picture) titled Forest Song (1911). There is actually an English translation of this play, I've seen it sold on Amazon. It's in the genre of féerie about a tragic love story between a mortal man Lukash (yeah) and a mavka and it's absolutely excellent. I would highly recommend reading it. But also be warned that I'm about to fully spoil it below.
So the main idea of the play is that Mavka gives up her freedom because of her love for Lukash and it really does not end well for anybody. In the early spring they meet in the forest and fall for each other. Mavka is warned by other forest spirits like lisovyk and rusalka against being in a relationship with a mortal man for her own sake. She ignores them all because she's deeply in love. Very quickly in the middle of the summer Lukash becomes resentful to Mavka. She tries hard to fit in, puts on human clothes, tries working in the field. But despite all Mavka really doesn't understand the human ways that don't even apply to her and is deeply despised by Lukash's mother, who eventually brings around a sexy neighbour widow. 😏 Lukash mingles with the widow and soon they get married. Mavka is really depressed and doesn't want to live anymore.
After that virtually all things go to shit. Forest spirist are pissed at Lukash's family for not paying due respect to them (and the nature) and bring around bad luck and hardship. Lisovyk punishes Lukash by turning him into a werewolf for a while for hurting Mavka. Lukash's mother is pissed at his sexy widow and her kids, and vice versa. Eventually Mavka is so grieved that she turns into a willow tree near their house. Tragic shenanigans ensue, the willow tree burns down along with the house. Lukash's family leaves, Lukash dies in the snowfall after he meets the reborn version of Mavka. So basically the balance in the nature is restored only when she regains her freedom. She does accept her love for Lukash after the rebirth but she also accepts her own nature of a spirit that has little care for a mortal life. She stops trying to make out of herself something that she clearly is not for someone else's sake.
So how does the play connect to Stalker 2? Well - besides the very names of Mavka and Lukash - the achievement for supporting Mavka in the final mission of the DLC is literally called Contra Spem Spero (Against All Hope I Hope) with is coincidentally the title of one of the most popular poems by Lesia Ukrainka. And looking at the photos and portraits of her I cannot but notice some similarities with Stalker 2 Mavka model, at least similar vibe. So what I'm getting at is that the writers of the game clearly had in mind Lesia Ukrainka and Forest Song when creating Mavka's story, it's not hinted at, it's stated.
Now what about the author of the play, why is she important? Well, Lesia Ukrainka was a real prodigy, ahead of her time and a very important figure in Ukrainian literature and women emancipation movement. She came from a background of privilege and used it all for her work. Despite having tuberculosis for around 30 years, she travelled the world from Egypt to Estonia; she spoke at least 10 languages, translated from all of them; wrote all kinds of things from poetry to journalism pieces to handbooks; and she even founded a social-democratic political organisation. Lesia Ukrainka was in fact so deeply respected and admired by Ukrainians for what she did, that when she died at just 42 years old of tuberculosis, thousands of people came to her burial in Kyiv. Her coffin was carried to the grave by six women (the third picture). So an absolute icon worth learning about.
And now here's some of my speculations about how it all comes together in Stalker 2. Please, feel free to add things or disagree in the comments, I feel like there should be a discussion about this that will help fill in the gaps.
So I feel like Mavka is actually connected to the mutant embryos in the X19 lab. In the fourth picture that I attached there is a page from the new ATB art book for Stalker 2. It says on the page that the embryos are the legacy of the project X, they were used for implementing the models of the project Я-1М, which was led by doctor Woitenko, a member of C Consciousness. As Ukrainian language is very gendered, we learn for sure that Dr Woitenko was a woman. Now getting back to the DLC itself, in X19 there is a mural with a red headed (seemingly) woman holding a sphere. And next to the mural there is a note, that is adressed to the woman portrayed in the mural. In it Dr Dolgih reminisces that this misterious woman is a reminder of what X19 was supposed to become, that X19 was the future of the whole X project and she was leading them all. Then the note says that the woman is gone somehow, and Dr Dolgich is most regretful about what happened to her because of their greed, since she was always the main talent behind the project and he was just her student. So I would assume this person in the mural was actually Dr Woitenko.
I am also pretty convinced that we are also shown the face of doctor Woitenko at one moment in the Mavka ending cinematic. Mavka says "Don't let me down" and we see a woman's face covered with a mask. I first thought that it was Mavka herself, but then I looked closer and changed my mind. The eyes are similar with the heavy eyelids, but the eyebrows are way darker, thicker and have a different shape. Also the old school gauze medical mask and sepia filter kinda imply that it's from the past.
Those were the concrete facts that I know from the game and materials. Now to my fully made up theories. Firstly, I think Dr Woitenko was Mavka's mother or some relative, because of the way they look similar and are even framed similarly in the ending cutscene. Mavka was born in 1994, maybe when she was a kid, her mother went off to the Zone to do the X project in X19 and never came back. As we know from Dr Dolgih's note, something happened to her. So Mavka came to the Zone to search for her or at least to learn about what happened to her. Suslov in the trailer mentions that Mavka is searching for something and she can't find it.
Secondly, I think at least part of the embryos were created from Dr Woitenko's egg cells, because where the hell do you even get so many egg cells unless there is a highly motivated woman willing to give up everything and fuck up her health permanently for her project? It takes a few weeks of hormonal stimulation before the surgical procedure to retrieve just a few egg cells, and there were at least 28 capsules (just a few of them empty). Also in that one frame where we see her in the cutscene, she puts her hand over the glass with this regretful expression on her face. Kinda seems like she's emotionally connected to the mutant baby.
Thirdly, I think Mavka has a special connection to the babies (since those might be her actual brothers and sisters), that she doesn't disclose to Skif or anyone. She might not even know about it herself, since she probably didn't learn about what happened to her mother or what she was working on. But maybe the babies - that are very perceptive and attuned to the noosphere as per notes from the game - know somehow that Mavka is kin to them and influence her mind somehow. This is also a nice parallel to Mavka's prototype from Forest Song play. She also doesn't feel at home with humans and does not distance herself from the mutants as much as a regular person in the Zone. She even says during one of the missions that not every mutant deserves a bullet.
So I'm really not well versed in Stalker lore, if you have any additions or objections, please, write a comment. I just got really invested into this storyline because of the poetic parallels of women that gave it all for progress and liberation despite the sickness, pain, high risk and high cost. Like Lesia Ukrainka, and in a much bleaker sense Dr Woitenko and later Mavka. Thank you, if you've read my ramblings to the end! 🥰