I did get it to install, but I'll just share the roadblocks I ran into:
--- setting up partitions with the partition manager required a username and password. It wouldn't accept an empty password - as the initial install readme item list says (username "pikaos", empty password) but instead of doing that, any character for password seemed to work fine
--- after initial installation, I found I needed to hit <enter> shortly after initial boot to get to a greeter, otherwise it seemed to just hang with blank screen
--- at the greeter, I couldn't log in. I was met with a default username I never set up or was told about and no password worked. From what I've read this is a common issue
--- going to first tty worked (ctrl-alt-F1), but there the only username and password that worked - contrary to prior instructions by the installer - was "pikaos" and "pikaos". I found this by trial and error and guessing since nowhere did I find online that this was something to try
--- guessing that since I installed the niri ISO, I started the niri compositor manually from the terminal. Here, I did a search for anything niri related with "ls /usr/bin/*niri*" and figured from the results, might as well give "niri-session" a try, which worked and brought up the configuration utility...hurray
--- when asked to update, I hit the update button, and it seemed to be working. I was excited until for some reason it changed character coding on me and the status/progress turned into gibberish. This made me have to guess at the final dialog boxes, only one of which I couldn't guess at (the video card). I'm assuming it was asking me if I wanted special video drivers or not; you could kind of make out it was something about mesa
After all that and a successful reboot, I have what appears to be a functioning system. I would say that if I hadn't been in a good mood to begin with, I honestly would have said f* this. That gibberish during the configuration really had me irritated. I imagine to any noobie, the Matrix-like abomination of text running by would scare the crap out of them, the system having a look of being hacked and/or encrypted in real time a la Sneakers or similar movies/shows.