Soon as you have your app.json file in place and you have installer expo cli, you are able to proceed with making your Android app.
To make your Android app run
expo ba --no-publish
The console will ask you whether you want them to manage your android certificate, or you will provide them your own keystore certificate.
Follow the onscreen instruction. In the end, you will get a link to your Android app. An .apk file.
Download this file on your computer.
Go in Google Play Publish. If you don't have an account yet, you can register developer account on Google for 25$ one-time fee.
You can find official publishing docs on Google Support Page.