regarding "quantum resistant" ledgers, and not to be promoting bitcoin or anything, but you may find this article interesting...

Link: Is Bitcoin at Risk as Google and IBM Aim for 50-Qubit Quantum Computers?

Those involved in the cryptocurrency ecosystem should not lose sleep agonizing over the possibility of random people cracking the protocol. Best case scenario quantum computing is not poised to undermine bitcoin’s foundational technology. Worst case scenario, the technology to attack bitcoin is already here, but no one feels incentivized enough to crack it.

Nonetheless, there is a concern from security experts that the bitcoin protocol should upgrade from SHA-256 to SHA-384, which is a sufficiently more advanced form of cryptography. This would be done as a safety measure, just in case. That is why Satoshi Nakomoto ensured the algorithm could easily be upgraded and enhanced. He knew technology would steadily evolve and he wanted his open-source, peer-to-peer system to evolve with it.