Steam’s generally been fairly good as a company throughout its lifetime, primarily by its philosophy of not trying to tweak the service that makes them loads of money for random metrics. It should be fine until, well, Gabe Newell kicks it.
As for linux gaming, it’s certainly doable-- a more elegant setting though is either running a dualboot with something like SteamOS or its derivative distros, or with a less volatile Windows build like LTSC. While having to shut down the pc to game is annoying, I find it a lot easier to concentrate on tasks with a ‘gaming’ partition and a ‘work’ partition, though that’s not for everyone.
I do recommend a cheap mule laptop as your first linux machine, though. Most Linux distros thrive as a casual usage/productivity environment, and it really can facelift old machines.