The good thing about open source is that anyone can contribute.
Yeah, you won’t make any money out of it, but if your goal isn’t to make money, then you can team up with others to create your own Android dialer from scratch and that will be adopted.
There’s no vendor lockins possible
That’s kind of a moot point seeing how it will be adopted by 100% of phones at one point (except for phones which are out of support, but those won’t get used at all after a certain point)