Needs a way to make the radio output come from loudspeaker rather than headphones.
I don't use headphones as an antenna.

Also, is there a binary for the fmtx anywhere?

P.S. The N950 and N9 actually have a different radio chip (variation of the same model). The N950 one doesn't include FMTX whatsoever.
The N9 one does though there is speculation over whether it is actually connected to any antenna. You may need to rip open your device and mod it with an antenna to actually use the FMTX.