I'd fill the space with a simple chest of drawers.

get a basket for a few pieces of kindling and a proper rack for a few pieces of firewood.

Keep the rest outside.

Have to agree with putting a chest of drawers there and keeping a small amount of wood on a rack or stacked on the hearth. We have a floor to ceiling fireplace with a closet for wood with a cut-out access to the front, as part of the fireplace. Only used that wood closet for two years. Now firewood is stored either in a box (built to store the wood) in the garage, or stacked on the outside porch. You would not believe the critters that will come out of the dried wood in a warm house.

Thx. I was originally looking at small chests before I came up with the shelf idea. I’ll look some more.