Have you tried to integrate RTL_433 (https://github.com/merbanan/rtl_433) ?

I'm using it to receive information from a weather station that is not supported by RFXTRX and submit it to Domoticz via MQTT.

This is a cheap solution if you only need to receive data.

I'm using a cheap RTL_433 receiver to record information from a wireless weather station. In order to do so I wrote a small script that receives the information, does a bit of formatting and then publishes the information using MQTT. In Domoticz I've setup a couple of devices for Rain, Temperature ...