Both the Espruino and Espruino Pico boards (with Espruino pre-installed) are based on STM32 ARM Cortex M microcontrollers (STM32F1 and STM32F4 families). While Espruino's development is supported by sales of these boards, the STM32 hardware support is applicable to a wide variety of other STM32 microcontrollers.
A wide range of STM32 Discovery and Nucleo boards will run Espruino, see here for a list, as well as for download and installation instructions. It can also be ported to new devices relatively easily.
Espruino is Open Source with an MPLv2 license. If you're interested in using Espruino in your products please get in touch. We can offer consultancy work to help with both board design and porting.
Note: While Espruino is Open Source and can be used in your own designs, the Espruino name is trademarked. If you wish to use it to sell your products (or to direct your users to our forums for advice), you'll need to agree licensing terms with us first.