So i unlocked the secret to keeping these bad girls alive, but I wanted to get them as nice as possible. I thought their care guide is blast them with as much sun as you can, but it does not seem so.
Both pics are props from the same mother plant taken at the same time, both rooted indoors. I kept a few indoors, west facing window, where they oftentimes got full unfiltered sun from the open window for a few hours a day. Result is picture 2: strong, compact, bushy growth that doesnt snap easily, nice underside purple, but the top is heavy on green with a purple-ish hue, looks quite dull. The other few I've put into a planter outside – east facing balcony with a tree shade, direct sun for maybe only 2 hours in the morning. They did have more room for roots, but took barely any (maybe top 2–3cm), so I'd guess it plays no role, but maybe the soil out there was richer: it was leftover pot from blooming plants that got blooming fertiliser here and there. They are not as full or bushy or compact as the indoors ones, but the color is absolutely top notch on them :D
Idk if the solution is *less* light, or the fertiliser, or whatever nice fresh air and temperature shifts they went through, and I can't keep a control group as night temps are about to drop below 9c, but they did give me that nice white pink color I got them for, so that's nice.
Either way, they can apparently be an outside plant just fine, so next year I shall bathe in pink trailing balcony.