The main problem with Linux as a platform, is that it isn't. Linux is a kernel, with a platform built on top of it. And that's the real issue: Gnome and KDE are separate platforms; but so are Ubuntu and Fedora; but so are Flatpak and Snap; etc. Depending on your application, you will have to support several combinations.
For gaming, Steam OS fixes that. You can't target "Linux", but you can target Steam on Linux.
For gaming, Steam OS fixes that. You can't target "Linux", but you can target Steam on Linux.