You now know what Fastlane offers. So how about Ionic support with its hybrid apps based on Cordova?
Well, it won’t work out of the box. Here are some of the reasons:
Fastlane expects projects to be iOS or Android. Ionic/Cordova projects can be both, which is the first problem you encounter.
Fortunately, fastlane uses different file and folder structures for iOS and Android so the same setup can actually be used for both platforms at the same time.
Fastlane also normally wants to be installed into the native projects. But as these are a) generated with Ionic/Cordova projects (/platforms/ios and /platforms/android), b) handled as build artifacts and c) usually not checked into git, your fastlane installation and configuration would get lost with each new checkout of the project.
Fortunately we can work around this by supplying explicit paths to our native projects in /platforms and install Fastlane in our normal project folder that contains our www folder and config.xml.
The commands you execute via the ionic CLI are also unique for Ionic (ionic cordova build, ionic cordova prepare etc.) [same if you are using the cordova CLI directly for cordova build, cordova prepare etc], and so are of course not taken into consideration in all documentation of Fastlane (where everything is done with Xcode for iOS or Gradle for Android) and the published tutorials around the web.
This requires some creative handling of things and also usage of some plugins. But: It is perfectly doable!
Start by preparing your Ionic/Cordova project for Fastlane.