In earlier versions of the Wikipedia Android app, it was possible to search Wikipedia directly with a search widget on the home screen. For some reason this functionality was removed, but it was really helpful!
Environments observed
App version: r/2.5.190-r-2017-02-24 (from F-Droid)
Android OS versions: Kitkat 4.4.2
Device model: Samsung SM-G355M
Device language: Portuguese