Window cling

You just wet it and place it on and smooth it down.

I use one on my clear bathroom door (no windows) it stayed on fine for about a week... bought the application kit and followed the directions, you might have better results with a clear reposition-able spray adhesive

A window film will not stick to paint. You will either need to glue it or tack it. If you use a good paint, you really don't need to use anything to protect it.

I don't think the cling film will hold up on a backsplash, they make wall decals for kitchen backsplashes that will hold up better. Amazon has quite a few.... https://www.amazon.com/s/ref=nb_sb_ss_i_1_24?url=search-alias%3Daps&field-keywords=kitchen+backsplash+decal&sprefix=kitchen+backsplash+decal%2Caps%2C509&crid=1YQ2RDUAPKOF6