I would like to do Google Sign-in for a Fire TV app. Unfortunately I can't use Google play services for this so I need a work around. The only thing I could think of is have the login screen be a uiwebview Google sign in web page. Has anyone ever got Google sign in to work with amazon devices?
To answer your question, yes it's possible to do that using a webview by following the guide here: https://developers.google.com/identity/sign-in/web/sign-in Once the user is signed in you would get the onSignIn() callback in the webview which provides you with the user's details that you can send back to your java class to carry on with the sign up/in steps.
Would I do it? Not in a million years!
My main concern is that you would be affecting the user experience on a device that doesn't have a traditional touchscreen entry point. The 10-foot UI has a different interaction than a tablet or a smartphone (try typing a complex password without a touchscreen keyboard). Why should I put my users through ~200 remote clicks just to type an average length email address and password?
The convenience of Google signin is in the native integration with the Android identity system, where with a few taps you can grant permissions to read your userid and much more. Why don't you instead take advantage of a similar method, native to the Amazon platform? You would start with the assumption that a user on Fire TV is already logged into their Amazon account, which means that if you had the ability to read their email address and userid you could achieve the same as what you do on Android TV... and you do!
Take a look at https://developer.amazon.com/public/apis/engage/login-with-amazon
UX: it displays a "Log in with Amazon" button, shows the user a permission pop up and, once they accept, you will get a callback with some of their details. No need for a webview.