Umm, a lot of campers have a wallpaper type coating, not sure if they’re conducive to painting, but you could always test what you want to do in an inconspicuous place.
Depends what the walls are made of I suppose
Our 2003 camper looks like a nice kitchen out of the late 80s. Cabinets are nice but really dated. If I actually had the time and inclination ive thought about painting and then partially sanding the cabinets to look like a distressed or farmhouse style.
There are also solid color stain looking paints that look like wood grain. Could turn your oak into cherry or redwood or some other hue.
Flooring goes a long way. Presume the camper isn’t real new?
Lose the cheap look linoleum for some nice wood grain snap together floating flooring.
That stuff is pretty durable. I slapped some down in our mudflow as a temporary solution and that was 5 years ago of probably 50 trips a day people and dogs through the laundry room. And it looks new still save for a couple scratches.