I noticed no one asked the important question...
What systems are you looking to play? I actually have a TRIMUI Smart Pro, got it on sale for about 50 bucks. I think they are 60 or 70 now, I don't know. Anyway, it's a good little handheld, capable of playing everything up to PS1 and PSP and light 2D Dreamcast games.
It has a nice screen, is comfortable to hold, and can last about 5-6 hours on battery if you're not playing PS1 games, roughly 3 1/2 to 4 for PS1/PSP. It charges quick to via usb-c.
It's about the size of a PSP. It actually has two speakers, and you can install your own OS on it, like Batocera (well, a custom build of it) or Knulli Linux, basically Batocera. Of course, I don't know what you want.
All I can tell you is about the one I have. I absolutely love this little device, and when powered off, the battery lasts forever, about a week in sleep mode.
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Pic's of mine