This is kind of confusing, but I just want it so that when you open up the Inventory, a Gui shows up on the right, and it shows your player.
I really have no clue on how to do this, but kind of do.
You’ll have to clone/construct the player's character into a ViewportFrame, a ViewportFrame allows you to render objects in a separate viewport.
In case you are going to use the in-game character of the player, keep in mind that you’ll have to set Character.Archivable = true and then clone it.
There are plenty of resources you can refer to for help.