alt Hacker NewsSeems like you can
https://origamiusa.org/thefold/article/diagrams-one-cut-hept...
The one cut is to remove the perimeter of the square that lies outside the heptagon. Without the cut, you could make a crease, and fold the excess behind the heptagon.
My reading is that it's a convenient near-7 approximation someone developed, like using 22/7 for pi.
Certainly good enough for practical handheld construction purposes, but not geometric-proof-y stuff.