That's just not correct. There are plenty of crypto algorithms already, including hash functions, that are designed to be resistant/resilient against a function

That's just not correct. There are plenty of crypto algorithms already, including hash functions, that are designed to be resistant/resilient against a functional quantum computer. A PoW scheme can use any (well, at the very least many) of them. [1] https://en.wikipedia.org/wiki/Post-quantum_cryptography https://en.wikipedia.org/wiki/Post-quantum_cryptography