[Retr0id]

GrapheneOS may be de-googled but it is not de-blobbed, they rely on the vendor to maintain certain drivers etc. Hopefully the driver maintenance team is very separate from the bloatware installation team, but someone could reasonably worry that they're tarred with the same brush.

[microtonal]

I would guess that most of the driver development is done by Qualcomm for phones with Qualcomm SoCs. At least that is what I've seen looking at the firmware/driver bundles some Qualcomm-based phones.

(Of course, there is more, like camera firmware, etc. but they are typically provided through the hardware providers.)