Our wiki is meant to be suplementary to to the communities here on the main Lemmy instance. I am sure there are some that would fit thematically to what you would like to add to the wiki?

If you tell it upfront to the other moderators that you don't have much time to do actual moderation of the community, I don't see why this would be an issue? I am sure help for creating a wiki page for the community would be appreciated never the less. In the end, it's just a technicality for making it easier to modify the editing rights on the wiki.