You can actually change the boot logo on Pixl.js now, but it's not something that's been made available on Bangle.js. It would only show for a fraction of a second after power on though - and no other time.
Right now you could change it, but you would have to compile and upload your own interpreter firmware. That's not such a big deal to do though.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
You can actually change the boot logo on Pixl.js now, but it's not something that's been made available on Bangle.js. It would only show for a fraction of a second after power on though - and no other time.
Right now you could change it, but you would have to compile and upload your own interpreter firmware. That's not such a big deal to do though.