For me there’s a bit of a network effect where the polycule sprawls out into the distance. Partners have partners who have partners.
But for disconnected folks, it’s mostly been tinder (yuck), and a local meetup.
(Also this might be the first post? That or nothing federated yet)
Mostly just in dating apps. Maybe it helps that in in a relatively large city, but Tindr and Grindr usually have plenty of other poly people. FEELD seems pretty feared towards polyamory.