Tried it: Yes! Radioddity FS-T3 actually works with RB18 driver. But it's not perfect. It's limited to 22 channels, while the real radio can handle up to 99 memory channels. 22 seems to be hard-coded in the RB18 driver. This is sort of a big deal because the radio offers no way to change squelch tones / codes without using a computer. Sometimes it's easier just to add another channel for a particular group or event.
Just like there are other radios supported by this driver with 5, 16 and 30 channels, you can add one that supports 99 channels.
The channels for the RB18 appear 'hard coded' because "GMRS = True". For a 'full band' radio, just make sure that none of the specially supported services are set to True.
_frs = _frs16 = _murs = _pmr = _gmrs = False
If you base your subclass on the Radtel T18 model, you will get this for 'free'.
Jim KC9HI