Loaded 1265 photos (more to be added) onto a 1st gen iPad bought cheaply from a pawn shop. It’s been set up without any Apple ID as it’s only intended for use as a picture frame.
Easy operation. Switch on ffrom off or standby, same button used there. If the password prompt appears, tap Cancel. Next, ignore the slide to unlock and tap the icon immediately to the right of that.
Enjoy slideshow.