Nostr is part of the fediverse through nostr:npub108pv4cg5ag52nq082kd5leu9ffrn2gdg6g4xdwatn73y36uzplmq9uyev6’s mostr.pub and upcoming ditto gateways. So when Threads supports ActivityPub then we’ll get to be able to follow and reply to Threads users via the gateways. They’ll see nostr posts eventually and vice versa. Replies and conversations should flow back and forth.