It's a work in progress. The Fender expression pedal and multi-effect switcher control my Fender Mustang GTX-100 amp—I use the reverb and modulation effects in the amp. Feedback welcome! : r/guitarpedals
Fender Mustang 1 V2 footswitch demo - a straightforward A-B pedal that you need to own - YouTube
EXP-1 Expression Pedal | Parts
I've made pedal/looper for controlling Fender Mustang LT25 effects : r/diypedals