Basically, I want a fast payload so I can connect to a device (for example a laptop) and then use my flipper as a remote mouse, keyboard, or media controller…
I’m not familiar with ducky-script, but if what I want doesn’t exist I would be happy to get some pointers to do it myself 
Thnx in advance
To write the payload learn what keys you need to press on the keyboard first. Note any place there might be a delay. I usually write everything down in notepad. Then I follow what I wrote exactly to see how it works. Once you get it working use the docs to translate it into ducky script. At that point you can test it with the Flipper. You will probably have to use the delay command in a few places so the computer can keep up. You will probably want to force the computer to forget the Flipper between tests if you want this to work on devices that have never been paired with your Flipper.