a) Using #Bridgyfed, to test between AT ( #BlueSky ) & AP protocols (Mastodon, etc.)
b) Meta's #Threads for testing with Mastodon.
c) Starting to test #Nostr with its peer-to-peer network.
TL;DR:
The #Fediverse holds a lot of promise, but it the ideal level of interconnectivity isn't there yet. (And yes, not all of them need to be able to connect and interact on the same level of details as with the others, as they are different tools.)