Wasn't khaled talking about non-custodial non-2fa wallet with multi-sig support? (based from "the closest thing")
In which case, instead of using a 2fa authenticator app, the second cosigner will be on that device instead.
Hmm maybe; but all the 2FA wallets that exist and are considered non-custodial are using a third party. For example Electrum uses 2of3 and the third party is TrustedCoin or GreenWallet uses 2of2 and Blockstream is the third party.
Additionally if the user owns all the keys keeping them on separate devices, it is no longer called 2FA, it is just a multisignature wallet.