Messages are private on signal and they cannot be connected to you through sealed sender.
No. Signal's sealed sender has an incoherent threat model and only protects against an honest server, and if the server is assumed to be honest then a "no logs" policy would be sufficient.
Sealed sender is complete security theater. And, just in case it is ever actually difficult for the server to infer who is who (eg, if there are many users behind the same NAT), the server can also simply turn it off and the client will silently fall back to "unsealed sender". π€‘
The fact that they go to this much dishonest effort to convince people that they "can't" exploit their massive centralized trove of activists' metadata is a pretty strong indicator of one answer to OP's question.
You can just make a group for each contact with all of your (and their) devices in it.