Yes, this setup has a NAT64. I can connect to IPv4 addresses with the prefixed IPv6 IP address. I just need DNS64, which should not be an issue. All the docs mention that the DNS64 servers first check for an IPv6 address, passing what is found, or reverting to a prefixed IPv6 if not. On an IPv4 network, the first step can be skipped & this setup will serve.
If you are expecting to get DNS64-prefixed IPv4 addresses for all domain names (and not native IPv6 addresses, since you have no IPv6 connectivity) you could just adapt some DNS proxy code to translate AAAA requests into A requests and add the prefix (fixing up the reverse PTR queries is a bit trickier but you might not care).
Eventually, we might add a parameter to the Google Public DNS-over-HTTPS
service that would allow you to request DNS64
translation (rather than enabling it based on the anycast address you sent the query to) and at that point you could adapt one of the many proxies that support DNS-over-HTTPS to get this functionality. However, that is a very low priority and we are unlikely to implement any such feature in the immediate future.