Are all private keys required to create a multisig bitcoin address Do all 3 private keys in a 2-of-3 multisig wallet have to exist on the same device at some point in order to generate the bitcoin address?

It would be ideal if the 3 private keys never existed on the same device together but it seems the examples I've found assume all 3 exist simultaneously when generating the bitcoin address and redeem script.
You do not need private keys at all to generate multisig m-of-n address!

You do need public keys. Yes, three for m-of-3 and eleven for 5-of-11 (for example)