UPDATE: Yes! Currently this feature is only available for Windows 10 and Android devices, but it will be rolled out to all versions of FulGaz in the future.
To do this, you will need to turn on Separate Power Meter Support.
Click on the settings "cog" in the top right corner of the main ride screen, then scroll down and select Advanced Trainer Settings.
Check the tick-box next to Separate Power Meter Support.
Exit settings, shut down FulGaz and re-start the app.
You should then be given new pairing options when you open the app again. Now you will be able to select your smart trainer as the controllable source and your power meter as the external power source.
NOTE: Windows 10 supports Bluetooth and ANT+ (where available), whereas FulGaz on Android only supports Bluetooth for this power matching feature.