When you have a 2-of-2 multi-sig wallet with someone, all you need to know is your mnemonic and their xpub.
Example: open your Electrum Bitcoin Wallet in --signet network mode. Make a new 2-of-2 multisig and as the counterparty use my (read-only) key Vpub5fzukEDJ7Q57QrhKMeMyRUkwHAHWTKAHwcdXdjvL9DFfkJqWrJPxqXN2afiCJ2dMabKxCUaXiFByyWgz9DvvnSRDdGRkSwJbCnx4UZ3gdnY. If you send any coins there, let me know your "Master Public Key". Otherwise there is no chance for anyone to find out something was sent to our wallet (or even that it exists).
--signetnetwork mode. Make a new 2-of-2 multisig and as the counterparty use my (read-only) keyVpub5fzukEDJ7Q57QrhKMeMyRUkwHAHWTKAHwcdXdjvL9DFfkJqWrJPxqXN2afiCJ2dMabKxCUaXiFByyWgz9DvvnSRDdGRkSwJbCnx4UZ3gdnY. If you send any coins there, let me know your "Master Public Key". Otherwise there is no chance for anyone to find out something was sent to our wallet (or even that it exists).