Houseology (here on Houzz) have done some renovations that included narrow halls. You can also go to their website and look at their section on halls: https://houseology.ie/hall-design-ideas/. There have also been some discussions here on halls that you could peruse. Good luck!

It sounds like you already have some great ideas! Half height panelling works well in long hallways, and is more practical than wallpaper as paint can be cleaned or touched up if it gets brushed against. A darker carpet or runner will define the floor and add height to the space, a shade that blends with the walls will add the illusion of width. A patterned carpet will help with flow and direction, which can make it feel more lively. Oversized art is always a nice touch to a smaller space (too many or too small and it can feel cluttered).

Best regards! If more questions, please do not hesitate to ask.

I think panelling would be lovely but I wonder if wallpaper as well may be too fussy in such a narrow spot?