I think signal is a good inbetween because its privacy focus, even though it uses phone numbers. Which as you said and i agree with it makes it less anonimus however picking apart that it uses phone numbers. you could also dig deeper and say that using any app on a device not made by you could have spyware in the OS or in the lower level permissions (bios, firmware) aswell as what if a government agency made a honeypot server that uses the protocol for simplex as example such as arcane OS and how it was sold as the most secure phone which ended up being a honeypot. so i think its fair to say its secure enough for normies who want more privacy focused but not be mr.robot levels, which signal claims to be private which it is minus the use of phone numbers. but realistically if in the examples given, if you where to message a Bad actor and said bad actor was arrested and they used signal to message you. all they can get is that they messaged you which wouldn't really hold up in court because although you where in contact with said person doesnt mean you where doing something illegal and if you dont incriminate your self (such as pleading the 5th) they really cant do a whole lot to charge you with something. which for those who know signal ownly knows the time and date of messages sent and online time as described in this artical https://www.dailydot.com/debug/signal-subpoena-privacy-gag-order/