[nebulous1]

> could do DMA on the video-game memory

The SGX won't allow you do this as the memory is encrypted

> plug the monitor HDMI cable into a raspberry pi 5 or 6

I don't know if the pi is powerful enough for that or not, and a HDCP type extension to what's coming out of the SGX could stop it, but ultimately yeah, you could have a robot play the game for you.

> stealthily modify the GPU drivers

Again, SGX type systems aren't going to allow that. This side of SGX type systems is all about trying to make your computer act how the developer wanted it to, regardless of your wishes or a malicious actor's wishes.