Notes on @takahe and #GoToSocial:
#Takahe search can find and view a GTS user profile. But follow requests don't make it to GTS.
Search can also find a public GTS post.
Takahe can reply, like and boost a GTS post locally. The reply and boost federate to Mastodon followers, but not to GTS,
GTS can do exactly the same with Takahe: search for users & posts, interact locally.
Basically nothing seems to be federating between GTS & Takahe at all except for search results.