It’s “different from”.

“Similar to”; “different from”; “less/greater than”. “Different than” doesn’t make sense.

Different app

It has video+audio calls but not push-to-talk and there are no “voice only”-rooms or whatever it is discord has

I never used Discord but used google hangouts before switching to Telegram and Matrix (the former for family and the latter for everything else).

No, only comments made after they refederate

You may need to shift your expectations of the federation model. It’s not trying to solve the problem of needing separate accounts on separate sites (that’s what we need portable identities for and I hope we see that in the near future). It’s trying to solve the problem of enabling self-governing communities and preventing platform lock-in.

I just want to add that I have another anecdote of this (not getting a response) happening to my partner. Don’t know if it’s a technical issue or they’re overburdened.