I’ve been using linux as my only OS since 2019 and like you came to the conclusion that it’s come a long way and is totally a viable option instead of windows.

Linux is great at running on old HW. I have a desktop I built in 2009 that runs linux.

I think older versions of the kernel (that support 486 hw) would still be available to download so someone could use them if they wanted. Not sure what other extre work would be involved though.

If you’re OK with using non-free/libre software I reccomend the systemcrafters install guide

https://systemcrafters.net/craft-your-system-with-guix/full-system-install/