I do a lot of work based around addressable LED’s using the Arduino module. Probably a bit to OTT for a car, but if you require any advice give us a shout as have done quite a few for others in my lifetime.
I recently intergrated LED’s in the rear of my Tuscon that can be controlled along with the front ones from the sat nav screen.
Something else to consider rather that LED’s ie EL wire. Its basicaly a thin flexible pipe with thin strip you tuck into your dash/door cards/gear selector etc with a LED hidden that shines down the pipe, so you have a strip that lights up similar to what you see in some new cars.