Getting back to an autonomous quadcopter build: compatibility

Hi everyone. First time here!

So, I started a quadcopter build a few years ago (about 2019 or 2020) and am thinking of returning to it. The main thing that I was trying to figure out before I left off is how to send commands to the flight controller (LUXF4OSD) either in Python or C++ via USB or TX/RX. Now it’s currently running Betaflight, and it’s built to the point where I can go into the Betaflight desktop app and send power to the motors and generate thrust, etc. It seems like the landscape has evolved from a few years ago and I’m wondering what the most straightforward way to control a quadcopter is from a Raspberry Pi/Odroid. I have the aforementioned flight controller which I’d like to use mainly for routing signals and maybe low-level PID control It seems like using Ardupilot and Mavlink may be the easiest way to do this? Is Ardupilot compatible with this flight controller or would I have to get a new board (slightly opposed to this as a lot of soldering has been done already). I’d like a solution that lets me send very low-level commands either voltage commands for each motor, or I’d be fine with reference velocity or the like if it that’s the standard interface.

EDIT: I would like to be able to read the IMU off the flight controller, but if that’s off the plate, I can use external sensors.

I’m a graduate controls student in EE, but I play more with math and simulation than I do with hardware and low-level code.

Any tips are appreciated!