This article says that attacking Bitcoin requires 1500 qubits:
https://en.bitcoin.it/wiki/Quantum_computing_and_BitcoinIBM Q System One has only 20, though they claim that they have better quality, meaning less errors.
I dont believe any quantum computers that are out or coming out anytime soon can break SHA256 yet.
When something like that comes out, we should have some time to react before it starts breaking things.
Dont forget that a computer that can break SHA256 is a huge threat to the entire internet, not just bitcoin.
For SHA256 there is currently no known algorithm that would give quantum computers an edge above classical CPUs, let alone ASICs.
Grover's algorithm? Not that it will break hash functions completely, but it will hugely reduce their security, so bigger hashsizes would be needed.