I don't know if it's possible to add a category without coop improvements

it'd probably work as a category extension. And you mean "No Upgrades" right?

Yes exactly No Upgrades

yeah it'd probably be fine for a normal clear, or coop category extension. I think 1CC and 2 loop wouldn't fit the purpose of doing a No Upgrade playthrough.

Maybe message the mods or link them to your post here!