To use an eGPU, a Mac with an Intel processor is required.
People have previously mentioned that for Apple Silicon based macOS, since the "GPU" is effectively part of the cpu they've gone with a shared memory model (for the OS).
If you try plugging in an external gpu to an Apple Silicon mac, it would need to understand "separate graphics memory". That's how macOS runs for x86 arch, but it's not the memory model used by Apple Silicon arch. Thus, failure.
That's my understanding of things from half remembered readings anyway. :)
Exactly why I'm perplexed when people are able to install USB drivers for MacBook Air's to be able to drive 2 displays one over DP & the other over USB somehow after a driver software is installed
There's a product called DisplayLink that's used with certain USB monitors and USB docks. It compresses the video displayed on the screen in a userland daemon.
It requires Synaptic's software and it does work as a solution for devices that don't have enough I/O capacity to support multiple DisplayPort screens.
Even if Apple did implement more eGPU support, their relationship with Nvidia has soured so badly that I don't expect their drivers to ever work with macOS. AMD cards may work because Apple has used their GPUs before, but even on their new ARM chips Apple has decided to forego support for AMD GPUs.
If you try plugging in an external gpu to an Apple Silicon mac, it would need to understand "separate graphics memory". That's how macOS runs for x86 arch, but it's not the memory model used by Apple Silicon arch. Thus, failure.
That's my understanding of things from half remembered readings anyway. :)