The following items are available:

for 2016 R1200RT:
OEM windshield CAD$300 (retails for CAD$750 plus tax)
OEM driver seat heated CAD$500 (retails for CAD$1050 plus tax)

for 2021 R1250RT:
OEM windshield CAD$300 (retails for CAD$750 plus tax)
OEM driver seat heated CAD$500 (retails for CAD$1050 plus tax)

Seats are essentially the same but the windshields ARE different.

2021 parts are as good as new.
2016 parts are barely used.