Agreed, I found infuriating that after 2ish years your android is no longer secure and you are on your own, and you have two options here, throw it away and get a new one that will be thrown away soon, or go in the efforts to find a hacky way to install a custom ROM that hopefully the maintainers will keep it secure. It’s that reason why I switched to iOS years ago.

Just buy Apple hardware.

They're currently bugging me about updating a 9 year old ipad I just use as a kindle. They flatly blow Google away on device updates, and will continue to do so even if Google isn't lying about their new / supposed 5 year update plan (and NB: that's 5 years from the release date, not 5 years from the last sale date, which could be reasonable.)