Niron is not developing an EESM. They are developing Iron Nitride permanent magnets. These magnets can be used in a variable flux permanent magnet synchronous machine (VFPMSM). Variable flux machines have some similar characteristics to EESMs in terms of their ability to change the field excitation, but they are fundamentally different than EESM in terms of how they do so. EESM change their field excitation and VFPMSMs change the magnetization state through stator current pulses. Their current/torque regulation control is also quite different.

There are other startup companies developing EESMs but not Niron to my knowledge.