As a tech community, we should really rally around a libre/free mobile OS and soon. Being beholden to corporations for our operating systems is antithetical to freedom.
It's so much harder to do on mobile, for multiple reasons: - Hardware is not very modular (mainly because of size constraints), meaning you have to purpose-build libre hardware if you can't/don't want to run on tech-giant devices (you can right now if you're forking Android; you probably won't be able to once it's replaced with Fuschia). - Developers' needs have always been a bastion for keeping desktop OSes flexible…
Almost all hardware is NDA. Even the Raspberry Pi has a lot of it's mobile-oriented chips like the VC GPU under a lot of NDA restrictions and binary blobs. There's basically Qualcomm, Samsung, and Huawei as the only companies making cellular modems and basebands, nearly all of which is closed source.