Earlier quoted context omitted.
Perhaps a EGPU via thunderbolt would work? (Not that GPUs are so readily available right now, but just to get N monitor ports as needed offloaded) Have you investigated that at all? I recently ran into something somewhat similar of needing "active" displayport adapters to connect more than two monitors at a time to a video card.
M1 Macs do not support eGPUs.
Another possibility is a device that merges monitors' and then presents as one to the computer intended for video walls.. I know of the ones that Matrox makes but might need windows to setup.
https://www.matrox.com/en/video/products/video-walls/quadhea...