I have a couple of friends that I message via Signal and even convinced my dad to use it a while back, but here in Brazil WhatsApp is _everything_, and I doubt most people care about this at all. In my case, I'd love to just go over to Signal fully but then I couldn't talk to family, friends, and probably couldn't even book a haircut or pay my taxes (my accountant messages me on WhatsApp).
It's one of those where unless just about everyone were to go over to Signal, most people won't, because keeping track of messages in two apps is quite hard.
That leaves me stuck in this ecosystem, which is quite sad.