Well, most of these run on Dosbox and you can download DRM free installer packages directly from their website, so there's that.
But the Linux gaming crowd here keeps telling me how well Lutris and Heroic are supposed to work when I explain to them that I use a Windows handheld while my Steam Deck is gathering dust, so I'll point them to this next time instead of just telling them those don't quite do it for me.
All joking aside, yeah, I'd love GOG having a better client overall, including a Linux port, but the quality of the packages and the lack of DRM easily trump that, so still buy these on GOG.