It’s not too difficult to establish a Signal account from a burner number from a prepaid sim card. I currently have a Signal account tied to a sim not in my name. Getting a burner with cash is an option. Or, if you’re lucky enough to live near a payphone and can gain access to the number, you can activate a signal with a phone call.
I read Molly is forked from Signal. Can I message Signal users from Molly, or do all parties need Molly?