Maybe I should try blendOS beta to then possibly use it as base for my distro (which is still a distro tailored for university and I have not decided if I should go into immutable territory or just stop at my super cool™ idea with tmpfs home directory...)

IDK, it seems a lot easier than to build my own immutable distro, and advertised out of box android app compatibility is a really nice bonus... But knowing linux all of that features cannot possibly work that well in practice, and I can set up something like waydroid myself...