I highly doubt there's anything pro-foss that's actually going to have any shot at forming a local group. Federated tech is niche, odds of 2 people in the same 300 mile radius is pretty slim. Let alone trying for 2 that are looking for the same kind of meetup etc...
So yeah sadly I think you pretty much gotta go with a garbage service like meetup, or even worse, facebook groups. Good federated services have to kind of lean heavily into the fact that we can pull from an international pool to make the userbase workable. Once you go down to local levels... you are pretty screwed.