They are also working to similarly kill custom ROMs. Just recently the GrapheneOS team mentioned that Google is no longer making their hardware drivers Open Source, and so compatibility with new phones means reverse engineering their own drivers - which is a big reason that custom ROMs support such narrow hardware options already and very often come with limitations and/or features that just don't work. At best, they figure out how to make it work, but it takes time and updates can lag significantly behind.

We have a lot of options on the software side for avoiding google (or android), but very limited options on hardware. We need open source mobile hardware support ASAP.