Mobian and pmOS do a huge amount of work wrt. bringing up overall support for OEM devices. The other efforts you mention mostly work at lower levels of the stack, focusing on supporting individual SoC's or IP blocks. Both are very much necessary, but if you care about polishing support for a specific OEM device the mobile distros are doing much of that work.
>>megous+k3
The point still applies. Do you really expect Linaro or Bootlin to be working on completing mainline support for the PinePhone, Pinephone Pro and other Pine64 devices? That seems like it would be a job for the distros.
>>zozbot+87
I don't expect anything. I'm just telling you how it is, as a maintainer of the pinephone kernel that most of the distros use, and the rest heavily borrow patches from.