What can be done without dismantling the wall

Recommendations

Are the walls lined with MDF panels on the frame?

In fact, it’s easiest and most reliable to remove old panels and replace them with new ones. In this case, the most difficult, long and dreary thing is the device of the frame, which must be mounted on a level. And since it already exists, then replacing the lining is a matter of several hours or days depending on the area.

Even a beginner can cope with the installation of panels on a finished frame

What else can be offered?

Paste the walls with self-adhesive film - the simplest thing that comes to mind (see alsoDrywall decoration for wallpaper: do it right)
Wallpapering. Since the load on the walls is likely to be large, it is better to choose high-quality wallpapers that are resistant to abrasion. Or wallpaper for painting. Or any, but after the glue dries, cover the entire finished surface with varnish.

Note. Wallpapering is not a good idea, as MDF panels do not have sufficient hardness and bend during smoothing and gluing paintings. It is unlikely that this work will be able to be done qualitatively.

Paste the walls with cork wallpaper (panels). Best of all - self-adhesive.

The cork is quite resistant to mechanical damage and abrasion

Facing the walls directly on top of the panels with new plastic or MDF panels, having previously set the location of the frame guides (crates).

These options are contrary to all the rules of decoration, so you will not find anywhere instructions that describe the technology of work. Therefore, I would consider them only as a last resort - if everything needs to be done very quickly and on a budget.

If you want to give the retail space a really solid and attractive look, it is better not to save. Moreover, you do not have to bother with the device of the frame, and the range of wall panels of very different quality, color, pattern and texture today is simply hugen