This is cool, but what if maybe I need phone calls too?
Let's say the only bottleneck is that it isn't implemented yet. But if it could be done, then maybe you would plug the virtual phone number into Signal and use as a phone service? If that worked and if you could subscribe to the virtual number long term, combined with PGPP (pretty good phone privacy), you could break free from cell phone tracking, which is potentially the last bit to being completely untrackable.
i haven't personally used this service, but check out https://silent.link