This is basically an art project. I'm using scrap pallet wood for the base cut to dimensions and drilled holes for the strands. Take 8 AWG stranded construction wire for the the actual tree. Add the tiniest LEDs I could find and wire them in using insulated magnet wire. Route all the wires to the base, add battery and micro controller of your choice.
Paint, glue and lithium battery with a charge circuit. ( I have non rechargeable projects)
All parts, including the charge circuit and Pico have been either recycled from trash or from busted or incomplete electronics.