So just learning more about building PowerApps on CDS. When I use a Person field, I kind of expected it to automatically render a People Picker (a la SharePoint). Am I missing something? Or do you have to custom build your own people lookup and place it into the field?
Assuming you are using the CDS as your data source, the User entity will contain all enabled users of that environment, much like the User List in sharepoint only contains people who have logged on to that site collection at least once. If you want to have a lookup to the User entity, then you can create a Lookup field to the User entity (which will build a N:1 Relationship in the background).
Unfortunately there is no way in CDS (that I know of) to have it function like a Person field, looking up the User Profile Service or even Azure AD. Maybe it would be possible to create a custom connector to an Azure AD service or use one of the Office 365 services that are available.