vervein

I saw a young American tech YouTuber, he would get an old iphone SE as a backup phone just so he could use iMessage with his friends. I'm not judging though, i think iPhones are nice devices just very limited.

oLauncher Clutter Free from F-Droid. It's super simple and fast on my aging low end phone. I save every bits of cpu/ram i can.

Try crdroid, it has a degoogled option You can also look for a telegram group based on your phone name, there will be more roms there

Niche but very valuable for me is: symfonium which is a very complete subsonic client. Prana Breath is a lean but featureful breathing app with a ton of different exercises from beginners to advanced yoga practitioners

Both apps are android only and are miles ahead of anything iphone can offer which is worth being mentioned imo.

I think something like alpine or void with a wayland based tiling window manager could be fun.

Depends on your expectations, it won't be as streamlined as amd/Intel but if you are not too picky it should be enough to have a usable machine.