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)
If it be apps you be using.
OkCupid has a decent Poly community.
FEELD seems tailored towards non-monogamy.
Maybe check around FetLife for some “munches” (vanilla social meet ups) and see if you gel with anyone.
I recommend Feeld. Also Fetlife.
I don’t know what happened on okcupid, but it is very quick to recommend me people in like Connecticut and Massachusetts. I live in NYC.