With this technology, it’s just the combination of fuel and exhaust that makes it unlikely to reach peaceful applications sooner. A user of this technology must be willing to tolerate (and cause) considerable inconvenience just to increase the range of their electric aircraft.

Fuel distribution would be an annoying but surmountable problem. Not the easiest, but doable. Sodium needs to be stored either in mineral oil or inert gas. Otherwise it will spontaneously oxidize quite fast. Airports would need sodium warehouses with specialized equipment (either oil baths to submerge it or an unbreathable atmosphere). Trucks with the same kind of equipment would be needed to deliver the stuff.

Fuel production efficiency would be a problem. I don’t know the efficiency of sodium production, but intuitively this is likely to be around 80% (plus road transport). Charging a battery from the grid is more efficient, so the user of this technology must either have cheap electrical energy (this might be true in future with lots of renewables) or be willing to ignore the cost of energy (military users will do that already now).

Finally, the debate over a caustic exhaust stream is likely to be non-trivial. I predict that people will be quite worried about the direct effects of NaO and NaOH air pollution - it’s one of those things which is clearly health negative, even if climate positive. Unsurprisingly, military users are pretty unconcerned about being health negative.