We have installed wallpaper behind glass splash backs on many occasions without any problems, the glass usually being attached by a thin beading of clear silicon applied around the inside perimeter of he glass, then fitted the day after the wallpaper install. MOST importantly the INSIDE of the glass be kept perfectly clean on install as even fingerprints will stand out

I see wallpapered ceilings a bit in photos. See example. I can't imagine that would be easy to do! An application I did like was wallpaper between dark painted rafters. It was really effective. I don't envy the person who had to do that job. Or anyone who wants to remove it later. In my previous home, every room had been wallpapered sometime in the 80's. All bedrooms, hallway, living room, kitchen, bathroom, toilet. Quite a process to remove! I don't mind wallpaper but I didn't like the ones in that home. I think wallpaper can work really well in homes with a grander scale. High ceilings, architectural trims etc. In smaller homes, a restrained use is more appropriate IMO.

I selected Neither - Reason. I think that particular room looks great because a huge amount of expense has gone into making that room picture perfect. It is unrealistic to think that the average home buyer / owner will have that kind of money to invest in a room. Generally I would never put wall paper on a ceiling. The only thing that has made this room work is that they have been able to invest a lot of money into making sure this room is "show room" quality by matching the paper and the carpet and all the furnishings. It is not a homely room. It is a room for a palace or for the rich and famous. You could not relax in this room and I do not think the average family would ever allow their family to use this room - most of us do not have "special occasion" rooms.

All depends on your style as to what would look good, minimalist, mid century modern, Japandi, coastal, boho, cozy , find something that flows with the rest of your house.