Can I play Nintendo DS games on my Nintendo 3DS?

It is not region-locked I've played European, North American, and Japanese games on European and North American DS DS Lites GBA-esque DS

If you are a fan of GameBoy Advance games, then the best way to play them might be on a DS

nintendo ds slot 2 Durable Original DS Game System; Includes slots for both Game Boy Advance Games & Nintendo DS Games Product Details Is Discontinued By Manufacturer: No

nintendo switch lite game card slot Includes Original Authentic Nintendo Charger Stylus and Original GBA Slot Cover and an Extra Brand New Authentic Nintendo Battery for Unit