For what it's worth, there are the top 50 most active groups listed at https://a.gup.pe. Also, if anyone on your server is following a group it will show up in ordinary searches as an account.
I'm trying to help the situation by listing as many active groups as I can at @FediFollows and https://fedi.directory/tag/guppe/ (plus these groups are listed in specific categories that can be browsed along with non-group accounts at https://fedi.directory).
oh I am definitely NOT belittling your highlighting of worthwhile groups @FediTips All the things you do for the fediverse are a huge value!