Provide a detailed and clear description of feature or change that you want to offer.
One more idea about special shulker boxes. Player will place 4-8 potions (needs testing for not too OP) in special shulker box for potions only and then can drink (or throw) directly from that item in hotbar or in his second hand one by another.

Describe why you want this. If there's a reason.
I'm sure most people don't like potions because they can't be stacked. I know there are mods for this purpose, but they haven't been updated for a long time. In addition, even those mods that exist combine only the same potions and that stacks is easy to get that's no good for early game balance. This item will allow you to create something like a potion combo and will make the gameplay more interesting.

And it also needs a little cooldown (about half a second i guess) between uses to prevent the player from accidentally using a throwing potion after drinking previous.
UPD: Maybe needs. Actually i don't know how a held down action button will work with this item. In short it should be: one button press - one potion use.

Fine idea, except it probably has no reason to be a shulker box. It may just as well be glorified potion-only backpack with limited slots but some additional functionality on top.

Marking this as "I dunno perhaps" primarily because I start feeling overwhelmed with all ideas that await implementation, both on this repository and in my personal list.

Fine idea, except it probably has no reason to be a shulker box. It may just as well be glorified potion-only backpack with limited slots but some additional functionality on top.

Now i think about that too. Maybe here it can be some other item type (not shulker). I guess my obsession with shulker boxes is due to the fact that this is the only item in the game that we can place as a block, fill with different stuff and mine it then without dropping anything. Moreover receiving it in late game only isn't good idea too.

Marking this as "I dunno perhaps" primarily because I start feeling overwhelmed with all ideas that await implementation, both on this repository and in my personal list.

It's fine. Everything has its time.
UPD: in 1.17 update they wanna implement Bundles. Maybe it will be time for that and this potion backpacks will become that type of item.