Consider Alice and Bob created the following native segwit script:
hash SHA256 defined as H | Alice PubKey | Bob Pubkey
Only Bob has the pre-image (plain text that hashes [sha256] to H). Can Alice just sign a transaction without revealing H, and just hand over the partially signed transaction off chain to Bob so he can reveal H + add his signature, make the transaction final and spend it?
The catch here is that neither Alice and Bob to be in total and exclusive control of the funds, but for Bob to have to reveal an additional secret as spending condition.