Jayb151ideas for deadspace behind fridge
Homelab. Or a pantry with deep pull out shelves. Or open it up on the side of the room through that doorway and convert to a built-in bookshelf or cupboard and close it up on the kitchen side.
I’d start with IKEA, for inspiration at the very least. A lot of their kitchen stuff is very modular, so they may have something that could fit in without too much fuss.