Jeremi777
I did this on my A4 last winter — short version: you can do either, but aftermarket plug-and-play modules are the easiest if you don’t want to touch factory wiring. I picked LED puddle lights that fit the OEM door trim and wired into the courtesy light circuit; install was tidy and reversible. Key tips: buy CAN-bus compatible units (no weird flicker), seal connections against moisture, and aim the beam so it lights the ground, not drivers’ faces. At night it looks premium, not flashy.