Sorry, I don’t have an ultra-wide screen so I can’t test it, but I re-uploaded the blend file with some post processing (with compositor) and added an ultra-wide version, everything is set so you just need to render the final image.
Link to blend file with compositor nodes
Link to blend file with compositor nodes (ultra-wide)
I might work on an earlier version of this scene that had toy cars, maybe it would look good in ultra-wide.
Link to original image