Is there any special reason you have 16 Witness-Vote Spots open?
I have very specific criteria for voting witnesses, without getting into details, the ability to protect the chain is paramount.
What are you using Raspberry Pi for most likely?
I have one acting as a proxmox cluster quorum vote and another acting as a PiKVM attached to an IP KVM giving console access to servers in the basement.
I have mostly moved away from Raspberry Pi's and most of them are in a box or my drawer as Mini PCs are far more practical these days unless you need GPIO pins or the smaller form factor of the Pi.