We're constantly improving Easy Tag. Here's what we've done recently:
Feel free to send us feature requests through the feedback form!
Easy Tag is a tag diagnostic tool, which let's you:
Whilst Easy Tag is good for previewing creatives in mobile web (use the QR code to open the preview page on your mobile), it might also be useful for you to preview your creatives inside an app, if you're running in app campaigns.
The "Creative Preview" app available on Android is the best option for this!
You can also learn more about the app on Google's help center.