Temporary job

I’m asking on behalf of a friend. He recently received his green card through EB-2 National Interest Waiver (NIW), about three months ago. His previous project recently concluded, and he is currently looking for a full-time job related to his professional background.

In the meantime, would there be any immigration or green card issue if he temporarily does gig work, such as DoorDash, Uber Eats, or other delivery jobs, while actively searching for a professional position?