invisible item

[rapid mulch]

I think the only way would be to create an 'invisible' texture for an item and add it to your resource pack. Then PAPER:1 could be your 'invisible' item.

[sacred tulip]

Do you use any plugin for resourcepack? Or just vanila

First, create an png as blank texture, the size is 16x16, named it anything you wanted.

Then follow this instruction

https://github.com/Simplexity-Development/Custom_Model_Data_Guide

[sacred tulip]

here's the texture

yes

16x16 is a size which fit minecraft inventory slot

Can you provide your resourcepack?

it's working fine tho

./give @p iron_nugget[custom_model_data=1]

im on 1.21.1