From vague memory of reading some data sheets: there are cheap little constant current LED driver modules for automotive applications. Two wires in: PWM power. Two wires out: the LED array. To get anything less than full output, you need to drive it with a square wave, and it might not function at a civilized frequency of a few kHz.

Doing better would require a different wiring design — there’s no way to just swap the driver without making the driver fancy enough to take, say, 50% PWM in and produce half current DC out. (Obviously this is trivial, and even available entirely off the shelf for non-automotive applications, if you have three wires in. But you don’t.)