As per the linked FAQ,
What platforms will Sid Meier’s Civilization VII be available on?
Sid Meier’s Civilization VII will be available on PS5, PS4, Xbox Series X|S, Xbox One, Nintendo Switch, and PC via Steam (which also supports Mac and Linux) and the Epic Games Store.
The Steam store (preorder) listing shows all three platform icons so I’m guessing they’re not just talking about making it work with Proton.
No mention yet of Aspyr (who ported Civ 5 & 6) as far as I can see.
The windows version of civ 6 runs better on Linux than the “native” version. I hope they do a better job with 7 but I’m not gonna hold my breath.