Many modern devices (GPUs are most famous for that but there’re others, e.g. printers) include their microcode/firmware/binary blobs as a part of their device driver. Technically you can reuse these binaries for different OS, but legally, at least if you’re on American soil, you can’t.
That’s ignoring stuff like filesystems, network protocols, shader compilers, or whatever else you need to get basic functionality out of the device.
Also, a given chip might require anywhere between 2-3 drivers (for something simple like a power controller) to hundreds + a stand-alone OS (for things with an embedded microprocessor, like a drive or some fpgas)
It is tedious work, but I’d love to see the BSD’s band together with a hardware manufacturer to produce a high end consumer-grade laptop with a 4-5 year production lifespan, and well-supported hardware.
There haven’t been any noteworthy hardware improvements in that space in the last 5 years (arguably a 2013 MBP is better than a 2018 one in most ways), so this isn’t as crazy as it used to be.
These laptops could be similar to Windows laptops also sold by the same vendor, which reduces engineering costs. Dell sort of does this for Linux, but they churn the models too quickly for the BSD’s to catch up, in practice.
The vendor could rotate a new model in every 2-3 years (maybe rotate form factors each time), and make it a sustainable business.
There is precedent for this in the embedded space. Look at PC Engines, for example.