Don’t know about wallpaper, but I’d be worried that using the same colour everywhere would look nice on some walls and not others, even with a neutral.
This is based on my experience with Dulux Fine Cream and Dulux Timeless.
I have Timeless in the back room, which faces south, and it looks the same colour as the upstairs of the hall, which is Fine Cream.
The downstairs hall is also Fine Cream… but one wall has quite a green tinge, which is not at all what I wanted (and the only bit of the hall I can see from the sofa).
Also, if you look at a paint colour comparison online, Dulux Fine Cream and Farrow & Ball Pointing are almost indistinguishable. But I had a sample pot of Pointing so I recently tested it against Fine Cream on the wall with the green issue - attaching a pic (taken with a flash).
Anyway, it could be worth considering two neutrals, one for south facing and one for north facing? (And don’t waste your money on Dulux 2-for-1 emulsion offers in B&Q, whatever colour you pick!)