I’d be more than happy to help you out with the install so long as the weather is good (or you have a warm place to do it). I’m not certified or anything, but I always do my work clean, safe, and hidden- no half assing.
Grab yourself a wiring kit, some of the loop or fork connectors (depending on the size and shape of the holes for the audio connection), and bring your tools and anything else specific to taking apart parts of the BMW.
We’ll get it done on a Sat or Sun.