SN allows crossposting. We have a PR that be merged soon that crossposts most post types via @bitcoinplebdev 

More will follow, but we are reliant on extensions exclusively right now which aren't available everywhere and can be painful to use in some cases. 

 Make SN nostr app interoperable with the other nostr communities apps for winning

https://github.com/nostrability/nostrability/issues/3