Got my #pinephone! I thought I would be using either whatever it came installed with, or #mobian as recommended by a couple people here. Unfortunately it turned out that #sxmo is doing quite a lot of things in ways that I like, and works much smoother than at least the default. I tried it before I even got to Mobian, because I did not expect to stick with it — the docs claimed many things either don't work or have very strange defaults. It seems they are slightly outdated though, as everything works pretty brilliantly.
The only thing I desperately need to use it as a main phone is a graphical #matrix client with E2EE support. It seems #fractal is still my best bet, but I still haven't gotten it to build to help with development...