New product is finally here.
Manual servo controller, with display.
Intended for quick testing of servos on your robot so you can easily find position values to put in your code.
https://www.tindie.com/products/irobotics/servo-controller/
Servo Controller by Island Robotics on Tindie

Manually control two servos. Features configurable range, a screen showing servo positions, and save/recall position buttons

Tindie