Why would you need to do that? The boarding pass has a QR code on it; the QR code links to your ticket. If you need to change your booking, they can email you a new one.

They are referring to gate and time changes

And? These are available on google, on the airline's website, and on screens throughout the terminal. Many airlines will send them to you via SMS. There's no need to have a whole app just to check your gate assignment.

Or I could just use an app and get a push notification.

If you have a half gig spare for such an app these days maybe

I can't remember the last time I received a gate change notification via SMS. App push notifications are more common in my experience.

Some airlines email you a hyperlink that put passes in your Apple wallet from a website. This seems like the ideal case to me.