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.