Steam actually kept support for windows 7 three years after Microsoft itself ended it's own support of the operating system. I can't fault them for finally calling it quits. There are no more official patches for these operating systems.

Games that worked on Windows 7 will continue to work on windows 10/11.

SteamOS is also a thing. And free I think. You might be able to limp by on that. I'm using the steam deck and pretty much my entire library is playable on whatever OS they are using.