The gap
WooCommerce sells any quantity from 1 upwards. Shops that sell in packs, need a minimum per order line, limit scarce items, or cannot afford tiny orders end up writing to customers after the order instead of stopping it at the cart, and many quantity plugins do not cover the block cart and checkout.
What it is
Packstep stores minimum, maximum and pack size on products, variations, categories and the store, combines them into one rule per cart line, and checks it in the quantity field, on add to cart, in the classic and block cart and at checkout, with messages that say which quantity to choose.
How you use it
Rules that hold in every part of the shop, inheritance that keeps the setup short, and messages that tell the customer how to fix the cart.
For WooCommerce shops that sell in packs or by minimum quantities and use the block checkout or the classic one, and want rules set once per category instead of on every product.