I am just a bit concerned about their attitude. If they were to release a decent open source Linux client with compatibility layers (just free ride Valve for now...) and commit to maintaining it, then I guess I am on the boat. Last time I checked the process was not very polished and games could be outdated.
Steam (via Proton) generally works, though, for those who wish to use it. (Steam+Proton also works with things downloaded from outside of Steam, too, and has for years[0].)
Proton itself is open-source[1].
If someone wanted to package up standalone Proton binaries for a Linux distro, then I don't see any particular barriers that would prevent that.
On GoG's part, they do provide the ability to just download a game with a web browser (the old-fashioned, DRM-free way). From there, I can manage the games I that own in any way that I choose.
Thus, I'm simply not seeing a problem here that needs solved. I already have the freedom to do whatever I want.
Which part of this situation is broken, do you suppose, and why does GoG in particular need to fix it?
It would be the best if they could provide a package manager-like experience (managing dependencies, auto-update, etc.). I don't like the idea that I have to deal with those issues myself even for popular contemporary games. Granted, I already have to put in some work running games on Linux so this might as well be what we get.
It sure would be convenient if retailers like GoG had awesome controlled support for various and sundry Linux distros, and for MacOS, and for the TRS-80 Model III and the Amiga 500, but:
What does a person buy when they buy a game from GoG?
In my own experience with buying from GoG: What I buy is a copy of a Windows installer, and [often] a Steam code.
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If I then want to do something on my Linux box (or my Amiga 500) with that Windows installer, then: That's on me.
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I don't think that they owe me anything else here. YMMV.