I'm the project manager of Parrot Sequoia. As Julien stated, we are developing a board, based on Arduino, to interface Sequoia with any autopilot.
Sequoia is fully controlled over USB using PTP protocol with some Vendor Extensions. The goal of this bridge is to translate PWM, GPIO pulses or MAVLINK to PTP in order to control Sequoia.
We decided to open-source the board and also the firmware on it.
If you want to help us on this bridge, feel free to contact me at email@example.com.