ADCs, DACs, IO extenders
These should all work without kernel drivers. For example, here’s a user space python library for ADS1*15 ADCs, or Nuvoton MS51 IO Expanders. Unless you need very specific timing or require the kernel to know about it, you shouldn’t need a kernel driver.
Also a solution: Use Wayland, it’ll probably break other things, and Nvidia support is only just getting there; but it’s multi monitor support is amazing, so it should fix that issue. So maybe it’s worth a try?