I was looking for an official website for the Android/iOS apps, but could not find any proper one. The item https://www.wikidata.org/wiki/Q4390943 links https://www.mediawiki.org/wiki/Wikimedia_Apps and https://www.mediawiki.org/wiki/Wikimedia_Apps/Team/Android/App_hacking and https://www.mediawiki.org/wiki/Wikimedia_Apps/Team/Android for Android.