I feel your pain as I did the same with my stainless steel oven. I rubbed some oil gently on it and it did help, but the t cut idea sounds good!

They’re fine to use otherwise they wouldn’t be manufactured. However glass is a better material. It will need templating and is more expensive than laminate but is easier to clean. You can choose a BS or RAL number to have the glass sprayed to, but if you leave it clear the colour of the emulsion on the walls will show through so you don’t have to worry in future about respraying it.

I have tiles on one wall by the sink, and mirror in a darker area. I also have wallpaper over the other (non-cooking) side of the kitchen. It's great!   Do what works for you.

Shutterstock [website] supply high quality images, either photo's videos, AI images etc and they're sold under licence on behalf of the original artist, so there's a massive library of images to choose from so you should be able to see the image before approval. Then the glass is screen printed on the reverse before going through the toughening process, all the glass i've seen which has been screen printed has looked stunning and i'd assume your glass supplier would have pictures and samples of their work [decent sized not little 100mm squares]. Cost wise though your cheapest option would be as Sonia says to go down the laminate splashback route which is a diy option.