Stacksmashing was able to get Doom running on an RP2040 with an LCD screen. I'd love to see it running on the Lily-GO board. https://usa.banggood.com/LILYGO-TTGO-T-Display-RP2040-Raspbe...

It has two buttons built-in and support for LiPo batteries. It might be possible to make this a teeny-tiny handheld device.