Disclaimer, I currently work at a zcash corp.
A separate issue is that both Monero and ZCash are not post-quantum secure, while many of the new zkSTARK VMs are. The ledger lives forever, and state actors will eventually decrypt the transactions if the cryptography can be broken. At that point it seems like it's better just to build the currency product in one of the zk VMs.
I'd need to review the design details more to say for sure, but e.g. from what I recall Pedersen hashes are used in the commitment tree, but not for nullifiers. Those use blake hashes (which are plausibly post-quantum secure), IIRC.
There's also the underlying prover layer, but many proof systems actually have information-theoretic zero-knowledge properties (assuming a suitable source of randomness), even if their soundness guarantees are based on assumptions like DLP.