I think something like this within your Power App might accomplish what you are trying to achieve:
Last(Split(DataCardValuePerson1.Selected.DisplayName, " ")).Result & "/" &
Last(Split(DataCardValuePerson2.Selected.DisplayName, " ")).Result & " " &
Text(DataCardValueDateTime1.SelectedDate, "HHmm") & "/" &
Text(DataCardValueDateTime2.SelectedDate, "HHmm")
It might take some finessing to get it fully functional with your setup, though.
If this gets you to the solution, please accept it 🙂