Question

This would make it easier to manage items using KubeJS or other datapacks.

Optional: Details

No response

Can't be done. Tags are loaded way way way after items are loaded. Blocks and items are created and loaded when game starts. Tags are created when a world loa. Technically you could have a tag that determines what goes in creative tab and what doesn't but for recipes, which are loaded at the same time as tags, you wouldn't have tags yet

He's right.

Tags, recipes, loot_table are loaded when you are logging into the world. OR creating a new world.

Understood. I'll close the issue.