Playdate. Once upon a time was named Game Boy.
Now it depends on what seems to be an Esp32 or similar. Sold for less than 10€. Development and everything considered, why would anyone spend more than 50€ for it? I didn’t know anyone needs a device like this. Otherwise I would have invented something with an epaper display. And with a solar cell on it. Play as long as you want in the summer time. Oh, and with background light for playing at night time without disturbing anyone.
Oh, most of this is included in any ebook reader - that cost much less and has a bigger display.
What exactly is that Playdate thing for??