I have been summoned.

If the question is about apps then yes postmarketos can run any linux executable compiled for arm. When you run it with a DE like plasma mobile you can run any normal wayland program like on desktop, but keep in mind the program must be display responsive otherwise it will be very hard to work with.

I don't know about a lemmy app but yes there are mail, browsers and YouTube apps that also scale properly to the mobile form factor.

Personally I wouldn't recommend waydroid unless you absolutely need it, for most things there is a native linux app.