Managed to get my hands on two executive arm implants, which I was planning to give to a Sanguophage that is decked full of Void cyber/bioware. Didn't see the option to install them so I removed the arms, still nada.

Strangely, using Dev mode to remove the hediff then add the missing limb ones allowed me to proceed with the installation.

Played around a bit and I think I spotted the issue:
Most arm cyberware/bionics are attached at the Shoulder, while the ones from this mod are attached to the Arm, making it impossible to install them on any pawn that has had their limbs replaced already.