There were eGPUs for Macs, but only the Intel ones. To my knowledge there are no drivers for eGPUs for Apple Silicon. My guess is that without Apple's involvement it would be near-impossible to get graphics accelerators working.

In theory you could make things work for some sort of computational acceleration (e.g.: AI, or some OpenCL work), but I am not sure that that market is really worth all of the work it would take. For those sorts of things it is probably a lot easier to setup an external (Linux) box, and send the work over.