So far I met the same PCI ID 1002:15d8 with 2GB VRAM which was working fine in
prime output mode with any nvidia gpu as provider. The mentioned version with
128MB VRAM doesn't work. No error messages regarding prime, just the screen
staying black.
https://devtalk.nvidia.com/default/topic/1056652/linux/amd-ryzen-7-geforce-gtx-1660-ti-laptop-gt-cannot-get-nvidia-to-be-used-as-primary-graphics/1