In order to load a custom OS you first must be able to unlock the bootloader ofthe device. The list of OEMs allowing that is sadly getting smaller and smaller and vendors are becoming actively hostile towards custom firmware development.
see: https://github.com/zenfyrdev/bootloader-unlock-wall-of-shame

won’t get better

There’s a common saying in Germany that applies. Basically translates to: “Those Brits are crazy”, but the literal translation would be: “The Brits are spinning” (yarn).

Obelix knows best.