Gauging interest and planning a local niche programming meetup in a new city

[Jonathan7]

I'm a software developer who recently moved to a new city, and I'm interested in finding or starting local community meetups focused on niche programming languages and open-source projects. I've checked the usual platforms, but most groups seem either too broad or inactive. For others who have built successful tech meetups, what are the most effective ways to gauge interest and find a core group of committed organizers? How do you secure a consistent, affordable venue, especially in a downtown area, and what mix of format—like structured presentations versus casual hack sessions—tends to sustain engagement over time? How do you handle promotion to reach the right audience without just attracting recruiters or becoming too crowded?