This keypad like you said won’t work with the Enhanced Keypad ZigBee DTH since it’s Z-Wave but neither will it work with the Enhanced Z-Wave Keypad DTH since it doesn’t use the same command classes like the Popp keypad.
This one uses a whole different set of classes from lock keypads. To make this more interesting, the current ST API’s don’t support all the core command classes used by this device to communicate so it would require a custom ground up build of the DTH to create a custom command class parser and then handle the communication.
It’s completely possible, just need some time and the hardware. If enough folks want it be happy to do it.
BTW, This keypad costs about $40-$50. You can get a ZigBee keypad thats smaller in size and costs about $15-$30. It seems to have a 104dB built in Alarm like the IRIS v3 with a 105dB alarm while the IRIS v2 has a 85dB. Both the Z-Wave and ZigBee keypads run on batteries for about the same life (the Z-Wave has an optional A/C adapter). Am I missing a feature?