Retro Handhelds
Retro handhelds are small devices that are designed to run emulators. They often run Linux or Android, and some devices (such as the Anbernic RG353V) even support both. Retro Catalog is good for comparing the devices. Rocknix is one of the Linux distributions for such devices.
I've been down the small Internet rabbit hole for the past few days.
While I'm not really into gaming, these devices would work as a good starting point for building writerDeck, cyberDeck and digital audio players.
I know there are "for hackers" devices such as CardputerZero, uConsole and PocketTerm, but they are often over $100. Retro handhelds cover a much wider price range, and some are under $100. I might be able to justify buying one of the cheaper devices.