Items cannot be used anywhere you want them too. There has to be a prompt first.
For example
You can put the bolt cutters in your hotbar and try to quick select them on the chain but they won't do anything, the inventory menu use icon also won't work. You need to examine the chain to bring up the inventory automatically, and then they will be usable.
The microwave only has one function, to open and close the door, same with the fridge, and drawer.
The cooking pot can only be examined once in the present and per vhs run.
The piano can only be interacted with once in the present and not at all in the past.
It has been confirmed there is a room behind the barricaded door in the attic sure to a glitch which removes the door but not the barricade.