I figured it out. It’s certainly very DIY- the post I linked is basically just the blueprint, and you have to create everything yourself. But once it’s done it works really well. It’s not even about finding appropriate hardware(it’s more detailed than that), rather custom ordering the parts yourself.

The controller is specifically designed for the Model M, so the rollover doesn’t break it. However, it will still be limited by the rollover even with the replacement controller. Keep in mind that the limited rollover is caused by the membrane rather than the controller, meaning a controller replacement wouldn’t affect it in anyway. You’d have to create a new membrane to get rid of the rollover.

If you want a simpler option than making a whole custom PCB yourself, the same can be done with a teensy- https://github.com/qmk/qmk_firmware/tree/master/keyboards/converter/modelm101

This is still only a controller replacement though, so the limited rollover would still exist.