- Unlock bootloader (depending on vendor, you have to do an online verification),
- flash a recovery.img,
- load into recovery mode (which, depending on the phone, might need extra work)
- wipe some caches,
- select new os/rom image,
- pray it doesn’t brick your phone.
You’d think someone would’ve learned a thing or two from the easy graphical installations linux and even windows have been offering since the late 2000s.
and only specific ones at that. not all of them from what i recall.
All of them that are currently receiving OS updates, and some that aren’t. They even support the Fold and Pixel Tablet.