itemcollection VS foundryvtt-magic-items

For DND5e, there's a couple options. Item Containers and Inventory+. Both work on v9, neither have been updated for v10. I believe Item Containers will work on it, but Inventory+ won't. Inventory+ has a new repo for v10 that hasn't started work yet if you want to track that. (I do, it's the better option for me.)

Inventory+ and Item collections seem to be the only two choices currently available, and while both could be worked into a useable form, neither plays nice with the tidy5e sheets that I've come to know and love.

Item Collection

you can use the module Item Collection to create containers in your players sheet, it adds also configuration to the container item about how to handle its capacity, max weight, actual item weight (for bags of holding and such where the contained items weight zero) and so on.

This is what you are after - create all type of containers and bags. You can set the fixed weight and anything you put in it wont change the overall weight on your character. Its great. https://foundryvtt.com/packages/itemcollection

I believe the Item Collection module may be what you're looking for. Make sure to check out the GitHubfor additional information.

Thanks for pointing that one out. I think I'll keep an eye on it as it matures. Note this warning from the readme:

FoundryVTT Magic Items - This module for Foundry VTT and specific for the DnD5e system, adds the ability to create magical items with spells or feats that belong to the item itself, such as staffs or magic wands, which will be automatically inherited from the character who owns the item.

Magic Items - Allows adding additional spells and such onto magic items directly. Very useful for items that function on charge systems that can be upcast, though a little tricky to work with.

Well there's your problem right there.

Magic Items might help you. I believe you can set it to use multiple charges and scale with number of charges.

a solution could be to code your cutom "feature" into custom magic spells and use the mod "magic items" which let you add spells to magic items with customizable charge cost per spell, number of charges, charges regained at x and so on

What you want is the Magic Items Module... it works with MIDI-QOL and DAE. https://gitlab.com/riccisi/foundryvtt-magic-items

Magic Items

There's an issue for this raised on the module's gitlab page: https://gitlab.com/riccisi/foundryvtt-magic-items/-/issues/82