Embarrassing, but I never knew that you actually have to activate proton in the steam settings in order to install games which natively don't support Linux. This kept me from switching completely.
Now I use Fedora with KDE and can also run MS games like AoE without any problem. Even the performance is often a lot better for example in BG3.
Privacy focused people use more often Linux so the percentage of Linux users for proton services might be a bit higher. I don’t care about a calendar or mail app but I think a proton drive client for Linux would be important.