If you're asking how to authenticate to an Android app with SQRL, it would be just as if the app were a browser with a web page (which, let's be honest, most of them really are). Just as logging into an app logs you into a backend server, the app would provide a SQRL link to that server, and the server would authenticate it.
If you're asking if there are existing apps that do this already, I'm not aware of any.
The Discourse app is one of these web apps masquerading as an Android (or iOS) app. It is tied to an actual Discourse based web site and basically, using the app, you log into the site and it activates the app (presumably using a cookie of some sort.) The TWiT.community site is a Discourse site that has enabled SQRL login via @josecgomez's interface between OAuth and SQRL.
SQRL was originally targeted at web sites because they are the ones that can most benefit. The idea of not trusting a site to manage your password (or, more likely, a hash of it) is the central premise of the origin of SQRL.