DIY FC PID setup help

Alright so I see that everyone in the FPV and drone community use expensive gear for their quads

I’ve actually been working on a DIY flight controller and drone. It’s been started since my freshman year, and due to personal reasons progress has been slow. Being a junior, I have acquired enough programming experience and knowledge to have a working quad. Additionally I have had more time to work on this

Anyway, I am creating my FC from Arduino. My question is, in the gyroscope + accelerometer (6DOF), how should I develop my PIDs?

My plan was this:
My sensor can measure both angular velocity and acceleration. I am very familiar with finding the orientation and the angle an object with the sensor is. It’s just basic trigonmetry. I know I can set the PIDs to monitor this change in angle given the acceleration on an axis.

But I guess one can use the angular velocity relative to which ways the drone was during its setup and the user essentially changes the Setpoint of the angular velocity to match desired input**

Note: I’m more familiar with the accelerometer part of the sensor, so I’m sorry if I was a bit confusing with the whole gyroscope explanation :upside_down_face:

Thank you in advanced