> None of the Linux vendors make their own laptops
Dell, Lenovo, Purism, Pine64 et al. do.
The two in your parent may (at least System76’s laptops are said to) use Clevo hardware, but they can still ship with custom open source firmware.
It’s also not as if Apple sells their own custom CPU at the moment. Even then, they’ll probably buy other parts from third parties (eg. they buy iPhone OLEDs from Samsung, though they’re said to calibrate them differently).
And finally, integration can be seen as a bad thing. It’s conducive to lock in (see above comment on ARM Macs ending Hackintoshes).
Dell's Linux laptops are not custom made for linux (they even still have a Windows key!). They just swap out the wifi card.
I'm pretty sure Purism's are just standard barebones too, but with some extra modifications like hardware switches. They showed how they solder the wires to the motherboard - if they'd designed it themselves they wouldn't have to do that.
Pine64, indeed, that's true. The enclosure is standard (the PB Pro is the same as my Chinese "ChuWi" laptop :') ) but indeed they made a custom motherboard. I really like that company.
So they can never achieve the same integration as Apple.