I am currently playing on the steam deck in 4:3 aspect ratio with acceptable FPS, if there are not too many players in the cities at least.
But even then its still playable! I have some of my settings on low (shadows, AA) and some others on medium (effects, post processing, textures).
All on lower res with FSR enabled. Graphics are good on the small screen and still OK on my bigger 24 inch screen. There is of course the option to play in more reasonable aspect ratios like 16:10 or 16:9, but then either the FPS go way too low or it doesnt look acceptable anymore.
Overall gameplay, harvesting, PVEing, crafting, smaller scale PVP etc. is good but I don't think mass battles will be a competitive thing on the deck : )
Easy anti cheat installed automatically and it all worked out of the box using Proton experimental, even if this game is not officially supported.