This is exciting. I chat rocket fuel with my child quite often and he is into hydrolox from water. The other big alternative is methane from atmospheric CO2, but separating N2 could result in fuel with a bigger bang.
AFAIK, IANAExpert, Haber process is very energy intensive and centralized. It would be helpful to crack the N2 in a more distributed manner and harvest the results and maybe in a more rocket friendly molecule than ammonia, like APCP feedstock.
https://en.wikipedia.org/wiki/Ammonium_perchlorate_composite...
Basically any energy store receives inputs and then performs controlled outputs. In the case of subterranean hydrocarbons that was solar from long ago (without prejudice against geothermogenic theories). How can we take inputs from solar, wind, water movement, geothermal or nuclear and store it optimally for a particular task?
For most purposes various electrical charge or entropy change systems are sufficient. For purposes that require high energy density and high sustained release, chemical bond changes are optimal. Nitrogen is awesome for this purpose and so a biological process for storing solar energy in separated nitrogen bonds is exciting.