I've been suggested on Reddit that a Teensy could work to run Fusée Gelée. I made some research and it looks like the Teensy 3.6 can have USB host support using this cable. This library is a complete re-implementation of the USB protocol. It could be used as a base to make a Fusée Gelée launcher - I checked the code and everything needed is there. As we control everything that goes through the USB port here (remember, everything is re-implemented in the library), there will be no compatibility issues. The Teensy has enough memory to store both payloads (the one you want to run and the intermezzo payload). The only drawback is that a Teensy 3.6 is not cheap, as it costs approximatively $40 (at least from France). I guess that in the end, somebody will sell a standalone Fusée launcher for less money than that anyway (or even a DIY kit using something else than a Teensy). But I am curious - I wonder if somebody on this forum own a Teensy 3.6 and have programming knowledge to try this ? All is needed is to embed the payloads in a Teensy program and then use the USBHost_t36 library to port this script. It could be needed to use fusee-launcher.py to generate the payload beforehand if the memory is short on the Teensy.