So, as already established my primary concern with the Pixel 4a has been a lack of an IP rating. However, it looks like my worries won't be an issue in everyday use. This includes getting caught in a rain storm on the Harley.
To begin with, I used black electrical tape to seal off the 3.5mm aux jack. Since the jack is atop the phone, I did not want to provide an entry point for water for something I'll never use. The only other significant opening is the USB port, but it's on the bottom of the phone. While anything is possible, it's highly unlikely water would enter the phone through the USB port in normal use on the Harley. Potential weak areas are the pinhole microphone on top, as well as the speaker grill above the screen. The other mic and speaker are at the bottom, on each side of the USB port.
The other concern is dropping the phone into a water puddle, sink, toilet, etc. Obviously that could go bad, but this YouTube video made me realize that the phone will almost certainly survive an accidental dip. The Pixel 4a took a lot of abuse without failing, and testing included a teardown to see how much water got into the phone:
Waterproof Test | Google Pixel 4A waterproof rating?
