I don't understand what point you are trying to make. Why should I care about storefronts that I can not use?

If and when they go about having Linux support, only then would they become relevant to me.

/edit:

Sorry, misread your message. I am not sure how you'd go about running games from those stores, or if that is even possible as I only use Steam.

I don't have Epic or Twitch accounts, but Gog works excellently -- there are several alternative clients (e.g. lutris) that let you install Windows games into a proton prefix through GOG with a nice gui. Plenty of GOG games are actually linux-native -- and they "just work" quite well, amazingly including lib / .so constraints -- they have a standard script that does quite a lot to fix this. If you don't want a nice gui, there are a ton of CLI downloaders that "just work" and save you clicking buttons a lot.

GOG Galaxy for linux is "in progress" and has been for ~7 years. Alas despite being the most-requested item by far in their feature-request tracker, I think it's unlikely to happen soon. Galaxy itself works well inside a proton / wine environment, and will auto-update Windows games.

Gaming on linux is great!

There's a program called Lutris [0] that will handle GoG, Heroic will handle Epic [1]. Not sure about Twitch games, though, as I'm unfamiliar with their offering. If you mean Itch.io then Lutris handles that too.

[0] https://lutris.net

[1] https://github.com/Heroic-Games-Launcher/HeroicGamesLauncher

Epic games come to Steam when they leave Epic Access, I had no idea Twitch could install games, and the games they'd support are likely the kind of trash I'm glad is being filtered out from other stores, and GoG is DRM free and therefore easily downloaded. Their client sucks anyway.

If it's not on Steam, you'll have to use Lutris. It's a slightly better experience than having all those stores on Windows, but not as simple as Steam.