I would caution against Wikimedia from personal experience unless we first get an enthusiastic working group to kick it off.
I have set up wiki’s in a number of places. A sparse, highly incomplete wiki doesn’t get the use it needs to grow and improve, instead it tends to become an out of date, sparse, highly incomplete wiki. We have wiki tools, from wiki posts in the forum, to wiki’s on our GitLab. Neither are as good as mediawiki. But hosting a good tools is not what is needed for a good wiki, what is needed is a good plan for populating it and a clear idea of what should be in it.