> postmarketOS has no hybris and everything works great, but no device has all the drivers

this is why halium exists. OEMs don't produce drivers beyond whatever kernel they ship with, so this is an attempt to build a system that leverages the crap they do ship.

> why stop at the OS?

Because the OS is the only thing you control. The reason the Librem 5 costs so much for a decade-old platform is because they didn't grab a predesigned device from another OEM. Doing everything yourself is going to be the only way to produce a first-class linux phone.