The Cybervision 64 probably couldn't be made to work with Amix. It's a Zorro III-only card and the readme for the third-party Amix graphics card drivers mentions this:
The limitation to ZorroII mode is because the AMIX memeory mapping
system can't deal with ZorroIII boards and the source for the important
parts is not prvided with AMIX... :-(
Looking at the NetBSD driver source, it seems to support all the Cirrus-based cards. Hopefully it would be possible to emulate all the different cards too. That way you could use a Picasso II/II+/Piccolo/Spectrum for Amix, but with NetBSD etc. you could use an emulated Picasso IV or Piccolo SD64. (Those can have 4MB instead of 2MB RAM, so they support higher bit depths. The highest Picasso II/II+ resolutions are only 8-bit.)