Can anyone let me know about the Amazon’s gated and ungated Categories?

You are not allowed to sell in some of Amazon’s product categories. Amazon pre-authorization is necessary for all gated categories and some ungated subcategories. To avoid the difficulty of gaining access to gated categories, the majority of vendors only sell in ungated categories.

The permissions or category approval process is also referred to as gating. Gated product categories are items that can be sold after being granted permission, which turns them into ungated categories.