There is a module in gamelib [0] which will automatically clone, build, and link raylib to your program. There are several other third party libs there as well, including SDL2 and Curl.
I have a Surface Pro 2 running with the linux-surface kernel [0]. It feels like it has some rough edges - you have to decide between having pen support or having touch screen support, and suspend can be unreliable. These issues may be fixed now. Also, I encrypted my Windows partition, and now it requires the key each time to boot up, so I recommend against doing that.
Overall, I do agree that the hardware feels quite nice, and besides those issues I listed, the Linux experience is quite good. I was very happy to not be forced to use Windows.
I'm not sure why you say it's a "quite safe" assumption that most games are written in C#. Unity's beginner-friendliness gives it a disproportionate presence online, while the vast majority of AAA games are still solidly C++.
If we eliminate all games with less than 1000 sales or something, I think it would be a very low confidence estimate.
I think perhaps they meant "most Unity games", where Unity was supposed to be implied by the context. It probably is safe to say most Unity games are C#, if we ignore the portion of the engine runtime that is written in C++, which makes sense for some metrics and not others.