Forgot to mention, if you use any spray-on product (be it MagiSeal through the foam lance or a spray-on wax etc), make sure you don’t get it on the windscreen.
Most, if not all products i’ve played with severely restrict visibility in heavy rain, because while the water pearls off, it leaves “microscopic” beads behind, making it look like your window is milky. In some cars it can lead to the front camera (the one the car uses for sign recognition, matrix LED light etc) becoming unusable.
Which wouldn’t be a particular issue, if it didn’t also make your wipers judder/jump.
For that reason i dislike Rain-X etc as well, never had a good experience with any water repellent on the windshield.
Prior: SEAT Ateca Xcellence Lux 1.5 TSI DSG MY19, VW Golf GTE PHEV DSG MY23
Current: Hyundai Ioniq 6 Ultimate
Next: we'll see what's available in 2028.