See the first message of TFA. The author complains that amdgpu has way too many linuxisms that make it impractical to port it to non-Linux ( unless you are already emulating Linux). On the other hand, the nv kernel driver is portable, up to the point that it is easier to port that to Haiku and then change the entire Mesa to use it than it is to port amdgpu (which wouldn't need Mesa changes).
See the first message of TFA. The author complains that amdgpu has way too many linuxisms that make it impractical to port it to non-Linux ( unless you are already emulating Linux). On the other hand, the nv kernel driver is portable, up to the point that it is easier to port that to Haiku and then change the entire Mesa to use it than it is to port amdgpu (which wouldn't need Mesa changes).