Yes, the technical aspects are straightforward, the conceptual ones might need a bit of chewing over.
The way I see it, each community would have their own wiki but an instance could also have its own wiki for FAQs and the like which would then also act as the top level, linking to all the different wikis so it would appear as one cohesive wiki. Admins could edit any page, moderators could only edit their own wikis. You could either have a system to allow users to submit a draft edit or you could do that in a post in the community. Unlike, say, Wikipedia, there probably wouldn’t need to be large numbers of edits to a page in quick succession, so community members could thrash out a proposed update or addition in the discussion.
So, for example, I started a Home Video community and so I might want one page for a list of boutique Blu-ray releasers and another for a guide to buying a multiregional Blu-ray player. Over on Reddit I created a list of third party suppliers of STLs for the game Star Wars Legion that was well-received (which reminds me I must copy that over) which could be worth a page. Those pages would tend to be relatively static - only getting an update if a new Blu-ray publisher or STL maker popped up.