programming some FPGA using Espruino/Pico

I had a look at those, looks like the fleafpgauno IS the arduino, it's an fpga emulating an arduino compatible chip. The shield is programmed by an arduino, but as far add I can tell it only interfaces with the flash, you still need to use your computer to create the bitstream for the fpga. I don't think there's any value in replacing the arduino with an espruino, it's just doing some translation and you don't interact with it at all.

I've previously wondered whether it'd be possible to write javascript and have it translated into logic and programmed into an fpga, but due to the bulky toolchains needed for fpgas and the difficulty in mapping javascript to some sort of hdl, it seemed like a lot of effort for very little gain.