It would be cutting out a massive chunk of Framework's potential customers to not even offer Nvidia GPUs.
I don't like Nvidia at all, they're a scummy company. But just offering their products as an option is not "openly hostile and offensive" to Linux users. That's a bizarre take.
Until modern times, Intel was the largest GPU manufacture, unless you include phones, then it was Qualcomm.
Now it's AMD, between computers, consoles, and the datacenter.
DGPUs for the desktop aren't really all that relevant for either AMD and NV's bottom lines, they're not major sellers. Switch sales also aren't enough to compete with combined Xbox/Playstation sales.
A lot of claims of NV's superiority is just marketing smoke and mirrors.
For things that are hyperoptimized for a specific vendor, it is usually for AMD, not Nvidia, because most of that time spent optimizing is not done for enterprise compute (as _very little_ optimization is done, companies just buy more GPUs instead of writing better software, under the mistaken belief that developer time is more expensive than GPU TCO) but for game engines.
Game engines that are highly optimized for hardware are doing it for the consoles, both of which are AMD.
The only thing superior about NV is their marketing department.