I think visual cues would be necessary too. It would be great to assign keys, but it is then limiting the group numbers to a max of 10, given that the number keys are the only real non confusing choice for a dynamic selection (think pretty much all games have groups/hotbars bound to numbers)
It is important to stick close to generic ux/ui choices. like it or not users expect things to work a certain way and changing that is a surefire way to make the game inaccessible to a group of players who will quit when it behaves differently to what they are used to. It also has to consider completely new users and how they work out how to play the game. Yes people learn keyboard shortcuts as they go, but relying on them soley is not a good idea IMO.
Also it could show indicators on any shortcut icons, and even if workgroups are not a thing in later expansions, the same shortcut/icon slots could be re-used for other selection shortcuts.
It could even just show favourites along the shortcut bar!! giving users a way to get to their favourite groups, charaters or whatever else is to come.
Regarding the wiki/info - I am not sure steam guides are the best choice for info to help improve the game in early access. They are however great to help new users have a better idea how to play the game better.
In terms of UI though, I don’t think a guide should be essential to play the game past the tutorial, and the thing this UI is lacking more than anything is discoverability.
there is actually a wiki at https://ancientcities.gamepedia.com/Ancient_Cities_Wiki which is currently full of stubs. If the claimed, the community could start collecting data about all the game assets and mechanics which could be a valuable asset for new and advanced players.