Shiplap or V-Groove panels?

That’s just OSB subfloor someone hung and varnished. Odd. Wallpaper won’t stick to it. Paint may not either. Take it down and replace with drywall or add some kind of tongue & groove.

Three or four coats of drywall compound might do it. Might need some sanding first. Ask a paint store, test it first. I'd recommend a pro do it Then a primer and two coats of paint.

You already have the "cheapest option" .................: (

I think painting is better. Let's try to find out the most suitable paint color for your wall!

We have the same thing in a guest house. Will be replacing the "chip board" with drywall or paneling. Sorry, but chip board just looks cheap.

Panel over it with bead board or something similar.

I am guessing here, but I think a 1/4 inch sheetrock may work to cover it. Spackle, sand, prime, paint.

I’d Sheetrock over it.

Drywall over it or better yet remove it and do a new drywall . it also is a good idea to post pics of the whole space so we get some idea of your style since shiplap is IMO a ship that has sailed in most cases.

Yep, it's OSB (oriented strand board). It's usually used as an exterior sheathing applied to stud framing and then covered with exterior cladding. Most likely the best thing to do is to cover it with gypsum board (sheetrock). Another poster suggested 1/4" thick. That might work. You might have to wind up using furring strips on the osb to get a smooth finish. I would have a contractor come over and give you his suggestions. Good luck!

Drywall or shiplap it.