How do I cover chip board inside my wardrobe and shelves?

You can seal it with polyurethane if you like the look.

It can also be painted. You will see the texture.

You might try wallpaper that is pre-pasted and add glue for pre-pasted paper but I'm not sure how well it will stick due to the sawdust mess you mentioned.

I would seal it and then cover it with contact paper.

Thank you Kathy & Ann for your suggestions....think I’ll go with the polyurethane look.

I think just priming it and painting it would help. I'd be sure to use a good bonding primer like this one, to be sure it stuck well to the board.

You can seal it with a shellac or varnish and stop the flaking. Or you can paint it with a primer as well.

Prime and paint or cover with contact paper. I vote for painting. Easier to clean.

The most attractive fix is a venere. Apply a venere to the surface to make it look like a different material all together. A thin wood venere is a common choice because it works so well. You buy venere from your local lumber yard. It goes on with contact cement and lasts a lifetime. https://youtu.be/BeFzAPik_68 this video should help