First thanks original designer for this model.
I made remix of original Christmas Led tree to fit LED strip that i have.
LEDs are mounted in “hidden" slot on the back, and powered by two AA batteries.
I think that kind of LEDs can be bought anywhere.
Mistletoe can be found here:
https://makerworld.com/en/models/62158#profileId-64653
Christmas sock can be found here:
https://makerworld.com/en/models/56285#profileId-57878