A GAHP model was only recently added to EnergyPlus and is available as of EnergyPlus v23.1.

You can use the HeatPump:AirToWater:FuelFired:Heating (and Cooling) objects, and there is an example file called PlantLoopHeatPump_Fuel-Fired.idf.

This feature is not currently available in BEopt, though you could use BEopt to generate a residential IDF file and then manually modify it.