When I was a teenager I bought an JXD S7800B and only originally used it to play NES but it was powerful enough to play some N64. I played a lot of Smash Bros for the N64. I believe I got it from a website called Deals Extreme back at the time.

What made me want to ask about this was seeing a device called the X6 on Ali Express which looked a bit like the RGB20S and thinking about all the systems that have been into handheld devices like the Dreamcast and PS2 (that you can occasionally see on Ali Express as well).

I'd link the Austin Evans video where he used a portable PS2 handheld but his titles are such trash clickbait I can't find it.

Edit: I guess what would qualify as an obscure device in my mind is one that wouldn't have a custom firmware or is a rebranded version of another device. Consoles and mods are also pretty neat though.