How can I debug my website running inside my Android and iOS apps?

You may use Safari and Chrome remote debugging to inspect and debug your webviews in your app, just like you would in a regular browser.

For iOS please check https://appletoolbox.com/use-web-inspector-debug-mobile-safari/ - it is the same process for Webviews running within your app. Your app must be running on iOS Simulator locally, or on a device plugged into your computer.

For Android please check https://developers.google.com/web/tools/chrome-devtools/remote-debugging/webviews

For this to work on Android, you will need a "debug" build of your app. By default, GoNative generates a "release" build for you, so that you can pubilsh it directly to Google Play with no changes required. To build a "debug" version, please see Building Android from source.