Ergodox is not on there
Ergodox is enough specialized keys that it's not very feasible with GMK MOQ. A one-handed ergodox kit is 19 keys, which means it would probably be around $40 to outfit both halves of an ergodox (assuming $1/cap). If ergodox users are content to use already-included keys for some of the locations on their board, that price could maybe be dropped to $30 for a board.
As a GB runner, you then need to decide if you are going to include an extra $30-$40 worth of keys in your base kit, or provide them as an add-on. If the former, that probably represents at least a 20-25% increase in the cost of the base kit, which I would expect to significantly hurt efforts to make MOQ. Smaller compatibility kits such as ISO (4-6 keys), 65%/75% (3 keys), or 1800 (5 keys) are easier for buyers to stomach, because they increase appeal by at least as much as adding an ergodox kit, but do so for a much lower added cost.
Alternatively, if ergodox is run as an add-on pack, you need to make MOQ of 150 for ergodox kits. If you offer a half-ergodox kit, you may be able to get by with 75 ergodox users, each buying a pair of ergodox kits. I don't have a good feel for how many people use an ergodox, but it seems to me that would be a bit of a tall order for any given set. Perhaps it would be possible with a really popular colourway -- an ergodox addon for Dolch or Hyperfuse might be successful, even if run as a standalone buy.
That said, it would be great to see GMK sets for ergodox become successful. I'd love to be proven wrong!