As long as the image data is coming from the cartridge and the instructions are obviously moving data that originated from the cart to video RAM or registers (I

As long as the image data is coming from the cartridge and the instructions are obviously moving data that originated from the cart to video RAM or registers (I don’t know anything about the game boy). M with something like the GB camera, latency is less of a concern though, so the cartridge could probably interrupt the camera periodically to read video memory.