Firaxis has announced that Civilization 7 has been verified for Steam Deck ahead of its launch on February 11. This will be the first entry in the series to get the full green checkmark seal of approval on Valve's popular Linux-based handheld.
Civilizations 5 and 6 are both playable, but with caveats on Steam Deck: The primary hang-ups for both seem to be text legibility on the Deck's small screen, and the need to manually invoke the Deck's keyboard for certain functions.
Neither of those is usually a dealbreaker for me when considering games for Steam Deck, though Civ is such a wordy series, I could see eye strain from small text being more of an issue than usual.
Like both of those games, the system's raw graphical grunt is not at all a problem with Civ 7—it has some very breezy and lightweight system requirements: I can't imagine it took too much development effort to make sure Civ 7 plays nice with the Steam Deck, and it strikes me as a no-brainer move too.
Civilization 6 was successfully ported to the Nintendo Switch after all, and the series' relaxed pace of play should make the transition from mouse and keyboard to a pad more comfortable than with other PC-first games.