well, if you cant find it i think you're required to make it.
i like to surf active new queues, so when looking for new instances/ communities i sort by volume of active users (MAU) on fedidb.org
and then again in the individual instances by posts in their community search. this gives a good idea of general activity type and volume on the instance.
if you really want to find those niche places that might not have much traction youre stuck using those fediverse search sites