Not the sense resistor, rather the gain at the feedback pin of the TPS63020.
The design is fully documented here rfhv-posts and many other places. The circuit is very generic.
After eyeballing the PCB photos and PCB traces it's certainly the same design, even the input protection.
Additional...
TPS63020 on an 18650 for Burning! WooHoo!
Can you tell that I'm a wee bit ExCiTeD ^???^
People, this is so totally sick for just $8USD, look!
https://item.taobao.com/item.htm?spm=a230r.1.14.16.22d83d19AM5moY&id=8391540513&ns=1&abbucket=5#detail...