How critical is the tape that covers this connector? I realized upon sealing back up my device that I forgot to re-install it. I imagine it mostly is there to prevent dust and moisture ingress?

Just a heads up: If you are like me and you have accidentally turned on your Pixel 4a at some point while trying to pry the screen, don't worry too much. I was able to just connect my display with the device on. Nothing will happen until you reboot, and then the screen will initialize.