My startup, pQCee dot com, has been working on a quantum-safe ECDSA based on the pre-image proof which is similar in design to @vbuterin post. We called it Signature Pre-image proof (SPP) and is patent-pending. It was presented at decompute 2023 (a side event from Token2049)
We started with making ECDSA signatures in PDF documents quantum-safe and our next steps include making ECDSA in Ethereum and Bitcoin quantum-safe based on the same principle. Watch out for our EIP to be available soon.