Summary

JST-PH 2.0mm pitch 2 pin PCB-side male connector.
Pins are 0.5mm x 0.5mm, ones from 2mm pitch pin header fit perfectly. Don't use ones from 2.54 pin header, they are way too thick for the mating connector.
May be printed with 0.4mm nozzle/0.2 layer height, but only use PLA with a well-tuned profile.

I've created this to make serial charging adapter for tinywhoop batteries (like this commercial one). Balancing connector on my adapter is also 3d printed.