Solve Google Play Device is not Play Protect certified issue

Recently google has google account login restrictions for uncertified devices. But Google provide a way to register our own devices.
Google Device Registration

I developed a app to automatically register device with google.
I have uploaded the source code to github.
Source Code

problem

Step 1

Open “GoogleDeviceRegistration”

Step 2

Check GSF ID is right, not “null”

Step 3

Click GO button, First time you need to sign in to your Google account.

After successful login, app will automatically jump to the device registration page, It will automatically complete the rest of the step.

After successful registration, you need to wait 5-10 min, and reboot your device.

Attention

After reboot your device, you may also get an error message, don’t care about it, try to start google play several times.

GSF ID show “null”

Thanks for all