The only small caveat that should go along with that: that there is no native IPv6 connection to the Internet, i.e. it is an IPv6-only hotspot with an IPv4-only uplink to the Internet.
So, while the basic behaviour should be fine, it's best to set up a full-fledged IPv6-only access network, to ensure you can test the usage of the native IPv6 by the app as well, and verify there are no unexpected issues. (If the app talks to the resources that are IPv6-enabled, that is).
NAT64/DNS64 is completely invisible to the endpoint - there is zero differentiation between how a client talks to a native IPv6 resource and an IPv4 resource. All of the translation is handled by the network/DNS, so if your app works with your device configured with only a v6 IP address while supported by a NAT64/DNS64 network, you're good to go.
So, while the basic behaviour should be fine, it's best to set up a full-fledged IPv6-only access network, to ensure you can test the usage of the native IPv6 by the app as well, and verify there are no unexpected issues. (If the app talks to the resources that are IPv6-enabled, that is).