Starting in August, installing APKs from unverified developers will require a new procedure called Advanced Flow. It involves enabling developer mode, rebooting the device, and waiting 24 hours with biometric verification.
After that, you choose: allow the APK installation for 7 days or indefinitely. The procedure is a one-time process and applies to all versions of Android.
Will the 24-hour wait stop you from installing APKs outside the store?
It is still going to affect us indirectly. The problem is that Google is demanding developers to go through KYC even if they are not distributing their app through the Play Store. Not going through with it means nobody with a stock device will be able to install their app, unless they do that crazy workaround Google claims is going to implement.
This means open source app developers will be called to choose between doxing themselves to Google, or keep developing for us, the 0.01% who is on custom ROMs. It's not hard to imagine that many will just decide to move on and invest their time on doing something else.