Intermixing different model Pis?

[RyanWor]

Not so much an issue but a question: I see the playbook uses "raspberrypi3" for the HA install. Is it possible to have a mix of RPi models in the cluster? For instance could a cluster be comprised of 1x Pi4 and 2x Pi3, or 1x Pi4, 1x Pi3, and a PiZero for the third node just as witness, or a two node cluster be 1x Pi4 and 1x Pi3? Is it possible to designate a node to only act as a witness for quorum? For instance if you have only 2 USB sticks ensuring HA core only runs on the first two nodes since the third node would not have the zwave hardware? Thanks for any input in advance and thank you for this interesting project.