If by individual LEDs you definitely mean individual and not runs of 3 LEDs, then I would: - flash WLED onto an ESP8266 - solder a data output and power lines

If by individual LEDs you definitely mean individual and not runs of 3 LEDs, then I would: - flash WLED onto an ESP8266 - solder a data output and power lines to the LED strip - go through the list of LED options in WLED until one worked - try displaying Red, Green, and Blue to confirm that the RGB order was right It would be pretty rare (I guess) to find a tree that was using a truly custom addressable LED strip with its own protocol