Loving BTT since ages now. First time I'd like to request something.
Would be great to customize what the double tap does using Apple Pencil with Sidecar on an iPad. Not so many apps has a function for it, I have thought just a global "undo" would be awesome.
I use as temporary setup on the move, iPad as unique Mac Mini screen. So far I created a keyboard shortcut with BBT to blindly launch Airplay Mirroring, and recently I made a little app that automatices the process on Mac Mini startup so the Mac Mini wakes up iPad like a normal external monitor.
Edit: An extra would be using custom gestures on iPad, but that may not be possible at all.