DS-i: just a lot worse than the lite imo. The camera and the few dsi downloadable games were not worth losing GBA back compat
PlayStation TV: had potential but was just a worse vita and mediocre streaming box.
Piboy: a weird raspberry pi 4 based handheld I had by a company called experimental pi. It was actually kind of cool, but they had their own custom software needed to run on the screen and they were really bad about getting fixes out, and some patches would brick the machine iirc. The company seems to be defunct now. The website is a 404 now