ROOT: How to allow "install unknown apps" by default for an app?

Since Android 8.0 adb shell settings put secure install_non_market_apps 1 no longer works because we now have to enable it for a specific app. I am using Android 9.0 and I have root access on my device. Is there a way (using adb or other means) to allow my app to "install unknown apps" by default? I want my app to be able to update itself without opening settings.