Get one that's deep enough to actually hold stuff

The most common mistake is buying a folding desk too shallow to work as a nightstand.

You need at least 18–20 inches of depth. Anything less and your lamp, phone, book, or water glass will be constantly teetering or falling off. A nightstand that can’t hold a phone is useless.

Second: make sure the desk surface has a lip or raised edge when folded up. Things slide off flat folding desks. You want that little ridge to catch a rogue charging cable or a falling book.

Third: mounting hardware matters. This thing will take abuse from you leaning on it as a desk and bumping into it as a nightstand. Go into studs, not drywall anchors. If you can’t hit studs, use toggle bolts