a option to see the block state of blocks with a hotkey (what is inside of a shulker without having to oben it)

You can already see the block state (even the shulkerbox content) using MiniHUD iirc

BlockState as a term in Minecraft context refers to the state of the block itself, ie. which block it is and which blockstate properties it has. This is what you see on the F3 screen for example, on the right side.

As for being able to see the inventory contents, if you mean in the world, then there is the Inventory Preview tweak (which only works in single player without additional mods to send the contents from the server). Or if you mean in the item form, then there is the Shulker Box Preview tweak in Tweakeroo and the same feature also in MiniHUD, where you see the contents when holding shift while hovering over the item.