Someone asked on the KickStarter as well - about maybe having an online emulator :)
In terms of graphics and bluetooth, a Pixl.js would be reasonably similar (just lower res and not colour).
Another option is to compile Espruino under Linux (on a rasberry pi?) and you can compile it with SDL support which will pop up a window containing the graphics.
I can have a go at an emulator at some point, but I'm afraid right now my hands are a bit full :)
edit: another option is to try and pick up an F18 smartwatch (which Bangle.js is based on) and try and reflash it with the new softdevice and firmware - but that's not something I'm supporting right now as there's a quite reasonable (10-20%) chance that the update will brick it and you'll have to crack it open and reflash with an SWD programmer.
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