[RandomBacon]

Purism pretty much is doing what you're suggesting.

They're working with upstream packages so that when you install Linux on it, it just works, no hunting for additional drivers to make it work.

Those apps already exist. Again, they're working with those apps to make the phone "just work" when you install the apps/programs/packages/whatever. They don't need to reinvent Firefox, they can let Mozilla focus on that, and Purism can focus on what they're doing.