The last thread of informed comments here on this:

https://news.ycombinator.com/item?id=42995429

Yes, that deflated my optimism.

Iron nitride is much more useful as a thin film coating. Bulk magnet tech just isn't there.

The only report of a bulk Fe16N2 magnet I remember reading about used a 2 GPa (300 kpsi) diamond anvil to compact the powder. I can see why that might be economically impractical right now.

Also there was a bombshell paper that came out claiming synthesis of bulk L10-FeNi which was later retracted [1] and may have put a temporary damper on interest in Fe16N2. It remains unclear which material will be available first.

1: https://advanced.onlinelibrary.wiley.com/doi/full/10.1002/ad...

2GPa wouldn't be hard to achieve in a production setting, as long as it's only needed for a second or two. You simply have a diamond anvil in your factory.

Or alternatively, you use explosives or shock waves to very briefly get the pressure needed.