Authorization in Xamarin?

Question

Mobile development

There is a xaml application portatype, the project consists of 2 parts

• test
  
• Test.Droid
  

The essence of the question is whether authorization by Google services is possible (keys received) through the test, logic and xaml without touching the Droid project, since then you will need to attach all this miracle to both ios and vinfon in addition, so the droid project does not touch except the manifest, I would like it to so everything is left.