Actually I do know how this works having worked directly in this field. What you think is possible here is not possible. The data available wouldn’t support being able to triangulate thousands of users, you would be lacking key data you would need (as I said before) and the processing time would be such that you could not get this analysis done so quickly. And even if you had access to the right data it is not pre-structured in the appropriate geofences, nor would it be filtered to specific users who entered those geofences. You would need to do a shit ton of post processing, you would need to correct for triangulation errors inside a venue, and more. It just doesn’t work that way and it sure as hell doesn’t work that fast.
And even if it did, it would not be some random dude on Twitter and Tik Tok that figured it all out.