Gregory's Server
This commitment to greatly reduced activity on X is really great to hear!
One suggestion -- among the emerging platforms you identify, the fediverse is unique in enabling organizations to achieve a measure of true sovereignty. You could set up your own server here, and make it easy for partners or sub-groups to get accounts.
I'm not suggesting doing so at the expense of being active on BlueSky or Threads, but it could be an experiment worth undertaking :)
@indivisibleteam
Just as an example for this kind of model, see the German server https://bewegung.social/ ("movement") set up by @digitalcourage -- it's now home to several civil society organizations like Attac, Lobbycontrol, Abgeordnetenwatch, etc.