As an experienced freelancer, focusing on motor control and embedded systems, I would be a great fit for your project. I have a solid understanding of Raspberry Pi programming which includes designing and implementing user-friendly interfaces for controlling motors, particularly in a remote configuration. Additionally, my extensive knowledge in stepper motor control resolves your requirement for smooth and synchronized movement among the 300:1 gearbox motors with microstepping.
One of the unique aspects that sets me apart from others is my proficiency in digital motor control. I have substantial experience working with step motors, BLDC motors, and DC motors in low-speed applications. My grasp on torque and speed loop generation as well as control algorithms makes me reliable for accurately managing and overseeing the motor operations precisely as you described.
Besides these skills, my diverse background in analog design, electronic design, power electronics, PCB design, Matlab simulations -- all contribute to strengthening my capabilities to deliver your desired outcome effectively. With me handling this project, you can rest-assured about receiving a high-quality solution that works seamlessly, is simple to use via a phone-controlled UI and displays the position and speed of each motor as required. Let's collaborate to bring your vision to life!