Someone started a convo here asking for c:fertilizers tag
neoforged/NeoForge#1135

The tag would be for collection Bonemeal and other consumable items that can grow plants. I checked and it looks like Bonemeal simply calls a method on bonemealable blocks to grow plants. So there's no place or need for a functional tag under modloader namespace. This would be more for simply collecting the items for categorization usages.

I'm asking the original user rn for their exact use case but wanted to post this here in the meanwhile for feedback while I try and figure out what exactly is the usefulness of this tag

Modder is using the tag to know when the item is a bonemeal-like item in their Farming Machine block. Their block then will call the growing methods on the crop block and consume the tagged item from the Farm Machine's inventory.

Minecolonies has compost which acts like bonemeal which was the motive for the request it seems
https://minecolonies.com/wiki/items/compost