Is there a list of these by country?

There is https://meet.hn/, which is a good way to bootstrap (and indeed, how I bootstrapped this meetup)

	▲	matheusmoreira an hour ago \| parent [-]
		Hey I'm already on the site! Used to have the link with my city on my profile. How does one bootstrap a meet from this? Just explore the map around my location and try to get in contact with people somehow?