@Otis_Scops @jblue @pvonhellermannn @DarkOptimism
The Cornwall UK crop in the 1980's that I referred to, we winnowed with 4 people, each at the corner of a large bed-sheet, tossing the seed high, during a light breeze. Mentioned mainly as a "grain" that can be harvested and processed without specialised machinery. The decorative flowers were also an incentive to try it. The downside is mainly that it is hard on delicate digestions - see the WP article. Lots of soaking, changing the water was our work-around; when the water no longer froths, the saponins are mostly leached out.
See #Quinoa, which is closely related. Both of the "Dock" family. As Q. is locally available as food and actually a bit cheaper than millet and I'm not so far from a region where it's commercially cultivated, I'll probably try that before amaranth, tho I've never grown it before.
https://en.wikipedia.org/wiki/Quinoa#Saponins_and_oxalic_acid