Powered by USB:
5V -> 500mA
3.3V -> 500mA
Powered by Vin:
5V -> 2000mA
3.3V -> 1200mA
You need to subtract the M5Stick's own consumption from these values.
M5Stick is using the AXP192 Power management IC, datasheet:
http://www.x-powers.com/en.php/Info/support/article_id/29
M5Stick schematic:
https://docs.m5stack.com/#/en/core/m5stickc
@klimbot probably powered his M5stick via USB.