This app was mentioned in 9 comments, with an average of 1.22 upvotes
No personal experience but this seem to be trying to do the same thing. (I'm pretty sure you can get Google Now to save/display boarding passes, but I don't travel all that much - and Google Now is now less helpful than it once was...)
https://play.google.com/store/apps/details?id=com.passesalliance.wallet
I've been using Pass2U for a while. I complained about the lack of Material Design and the dev listened and made quite some changes. It's smooth, simple and has Drive backup.
I use Pass2U Wallet, but there are plenty of alternatives in the Play Store.
https://play.google.com/store/apps/details?id=com.passesalliance.wallet
How does it compare to pass2u?
I use Pass2U, been using it since I switched from iPhone a couple years ago. It is compatible with apple passes.
https://play.google.com/store/apps/details?id=com.passesalliance.wallet
I found the best Passbook app is Pass2U Wallet. When I travel I put it as one of the quick launch icons directly on my lock screen. It can also show a notification when you're near an airport and such.
For other travel purposes, if you use Gmail and Google Calendar, Google Trips works great but I tend to prefer forwarding my plans to Tripit (search ) and use either the official Tripit app or one of the many alternatives that can connect to it like Flight Tracker
Try Pass2U, it's basically the same. You just need the .pkpass-file from your airline.