Comment by Maursault

To suggest it is merely lack of drivers is an oversimplification. There is a chip errata that prevents PCIe GPUs from working properly on Apple Silicon: the architectures are not compatible. Apple Silicon GPU drivers are deeply integrated into the system. Due to this integration, only graphics cards that use the same GPU architecture as Apple Silicon could be supported, and there just aren't any, and I don't see how there could be unless Apple developed one and released it.