

How do you mean merge?
It’s basically another messenger.
Signal is a great app to replace your messenger with. Keep in mind that it doesn’t save whatever media you post there in your gallery.
Matrix is another solution, but you’d have to self host that. I have no experience with it.
Threema is a swiss app which I think was pretty privacy respecting as well? It doesn’t use phone numbers either IIRC.
Signal used to do text messaging as well but they removed the feature. As they felt it was unclear when a message was fully encrypted ( signal message ) and when it wasnt ( text /RCS message ).
I don’t think there’s a privacy friendly chat app that also does RCS.