Isn't this surveillance?

No. Surveillance watches you without your knowledge and reports to someone else. Ambient shows you yourself. You see your own data first. By default, your employer sees only aggregate information about teams, never your individual skills profile. Sharing more is your choice, made in the app, and reversible any time. Nobody calls their smartwatch surveillance, because the wearer sees the data first and decides what to share. Ambient works the same way.