I want to sign an Android APK for personal/internal use, which will not be uploaded to Play Store. When I try to install my app, even if "Install from Unknown sources" is enabled Google Play Protect shows a further warning which says "Play Protect doesn't recognize this app's developer". I am able to proceed by clicking "Install anyway".
However there are open source apps, not available in the Play Store, which can be downloaded directly from Github. For those APKs I don't get that extra warning if "Install from Unknown Sources" is enabled, which suggests that Google Play Protect already recognize the certificate they used to sign those APKs.
How do I achieve the same for an app that I don't want to upload to Play Store?
For signing I created a keystore using the keytool and added it to the signingConfigs section of the build.gradle file and the APK gets automatically signed during the release build.