Should I notify my sponsor if certain project activities of a funded research project cannot be completed or have to be suspended as a result of COVID-19?

Yes.  Please follow the Sponsor Notification guidance located at https://research.duke.edu/notice-to-sponsors.   Examples of impact include: canceling a funded conference, inability to conduct fieldwork because of travel restrictions, inability to meet the scheduled deliverables or aims/goals/SOW, absence of PI or key person for more than 90 days.