This happens only when using ion-header-bar, ion-content, or ion-footer-bar directives, and their respective div classes (“bar”, “content”, etc.). None of it shows up when using the stock browser for Android 2.3.6. However, Firefox on the same phone works fine. As such, the Phonegap app also doesn’t behave correctly.
AFAIK, Ionic targets Android 4.0+. The directives that don’t work might use features that older Android WebViews do not provide. Reference.
@maximilian is correct, right now the main focus is Android 4.0+ and iOS 6+ (webkit mainly). We do have limited support in 2.3 but we’re not focusing our efforts there.