That's why Samsung Pay won't work for whatever reason google pay has been selected and I believe that once selected you can't access Samsung Pay. The only way to access samsung pay is to wipe your phone back to factory settings and when you select the Samsung Pay app for the first time your given the option of either Samsung Pay or Google pay you can't use both so you would select Samsung Pay.
If you use Samsung smart switch it may select google pay if that's what you used on your old phone but having never used it I can't be sure.
