Most Android devices should install the Envoy Screens app directly from the Google Play Store. This keeps the app automatically up to date and is the supported way to run Screens on Android. However, some commercial displays and signage TVs ship with a restricted version of Android that can't access the Play Store, but will still accept a sideloaded APK.
For those devices, Envoy hosts a downloadable APK.
Sideloaded apps do not auto-update. Any time a new version of Screens ships, someone with physical (or remote) access to the device will need to manually redownload the APK and reinstall it. Plan for that overhead before standardizing on this approach for a fleet. If your goal is simply to keep a TV connected without re-pairing it, a Device URL opened in the device's built-in browser is often a better fit than the APK.