Did you mean that you want the options of a dropdown control to be the values from a people picker field of another list? If so, then you could add this list as one of the data source of this app and then set the Items property of this dropdown control to:
This will show all the names of the person in "Person" column of List1.
But you also need to notice the column type of the field that you want to write data to with this dropdown control. Please tell the column type of current field and we will discuss about how to update this field with this dropdown control.
If my understanding is incorrect, please feel free to tell.
Community Support Team _ Mona Li If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.