The lineage case is problematic because the devices are often different requiring different drivers. If the individual devices that make up your phone had to compete in an open market instead of getting bundled I'm a complete system, there would be more consolidation based on economies of scale, and thus fewer drivers to worry about. How many GPU brands for your PC do you have these days?

A phone is a more limited device that isn't bound by the same constraints as a laptop. I don't think the case is as hopeless as you imply. Something like Ara: https://www.extremetech.com/computing/193256-googles-project...