I like 125 on my 29" but then it has a rather heavy tire. I’m sure I could do shorter with something like a Schwalbe One tire.
On the topic of cranks, @Siddhartha_Valmont found some interesting ones on the website we shouldn’t use for buying stuff:
https://www.amazon.com/PROWHEEL-Electric-BANGFANG-Standard-Panasonic/dp/B0CLCZT1GY
Nothing shorter than 127 but for this price, might be worth a test!