I'm jealous that the the Zhiyun Smooth 4 has a charging port close the phone and my Osmo Mobile 2 does not.  So I decided to install a USB port myself and it works great! I know this mod must void my warranty but that's ok.
Now my phone maintains a full charge at all times and no dangling USB wire that can interfere with the motors.
Only wish I could charge both units at the same time, maybe that'll be my next mod to figure out.

Hi, thanks for sharing your modification on your Osmo Mobile 2. Please be cautious about using or installing third-party accessories on your unit as this may affect the performance of your unit. Thank you for understanding.