Ok. so the only possible solution i can think of is to have the email or displayname saved in the text field.
Set the default selected item and default value of the combobox
If(
!IsBlank(Office365Users.SearchUser({searchTerm:ExtendedProjectTeam_input.SearchText,top:1}).Mail,
Office365Users.SearchUser({searchTerm:ExtendedProjectTeam_input.SearchText,top:1}).Mail,
youritem.request_for
)
and the datacard update also.
You cannot add Person value to a text field in the ways of Hovering over a Person. For this you need the people picker and Patch like this.
Person:{
'@odata.type': "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedReference",
Claims: "i:0#.f|membership|" & Lower(First(Office365Users.SearchUser({searchTerm:yourdropdown.DisplayName}).Mail).Mail),
Department: "",
DisplayName: yourdropdown.DisplayName,
Email: yourdropdown.Mail,
JobTitle: "",
Picture: ""
}