FF with uBO was the killer app that kept me on android. If Apple let me run that, I'd have bought into it years ago.
Have you considered messages.google.com? I think you need to use Google's messages app (not the Samsung messager or equivalent) but it does as you describe and supports RCS.
Can i share my history and bonus with my desktop, ie linux?
Oh, it's closed source ios/macos only? Yeah, no thanks.
I also kinda doubt it's compatible with most firefox addons, addons can and do rely on details of firefox that ios does not provide the ability to emulate.
Have you considered messages.google.com? I think you need to use Google's messages app (not the Samsung messager or equivalent) but it does as you describe and supports RCS.