can you use zk to prove two wallets have the same owner?

If they are from the same seed phrase, then yes you can. 

Otherwise it’ll be much more complicated setup, probably not worth it.

Working on building zkTLS infra/products. A ruthless empiricist and meme connoisseur.

http://opacity.network

A big part of aztec’s pitch is that you could zk something centralized like google auth, which could be used to tie two seed phrases together (not necessarily google specifically). It’s trusted but private and we mostly accept similar trust assumptions all the time.