I'd suggest a different approach. I'm not sure how feasible it is for your case but just my 2 cents.

Community building would probably be way more efficient if done in person. That would make getting to know each other way easier. It would allow 'water fountain' type of interactions; which you usually don't have online.

So, my 2 cents would be to find a park, or something else public (weather permitting) and gather there. It could also bring passerbys to get curious and gather more people.

Not everything has to have a technological solution. In-person interactions should be more important for community building.