That functionality only works with Google Keep. Google killed off integration with third party apps early this year.

I've just sworn off using it and using the app we were already using manually. Sort of hoping the year of voice will eventually produce a viable replacement because I'm sick of Google killing shit off and forcing you to use their app. "Be different, not the same" 🙄

That function for Google keep doesn't seem to work for me when sharing a list with others. Like if i have a list in my keep that my wife has access to, she can't use voice to add anything to the list