If the idea of having a uLisp interpreter on your keyring appeals to you, check out the Muse Lab ESP32 Keys. These two ESP32 boards are the size of a USB stick case, and they are supported by Release 4.7 of uLisp.
Muse Lab ESP32 Key
The Muse Lab ESP32 Key is based on the ESP32-PICO-D4 processor, with 4MB of flash, and it includes a ceramic antenna.
It uses a CH343P USB-to-serial chip.
Buy it on AliExpress here: ESP32 Key.
Muse Lab ESP32-S2 Key
The Muse Lab ESP32-S2 Key is based on the ESP32-S2FH4 processor, with 4MB of flash, and it includes a Boot button and a ceramic antenna. It uses the ESP32-S2 built-in USB interface, so it doesn’t need a separate USB-to-serial chip.
Buy it on AliExpress here: ESP32-S2 Key.
For more information see: Muse Lab ESP32 Keys.