Well, I have an Android app where I have the following until now: The login screen and a "Welcome" screen, the point is that when the user manages to enter with the correct email and password, I take it with an Intent to the "Welcome" screen, but by clicking on the "back" button You can go back to the login screen, which I do not want to happen.
Regularly Login or Splash screens initiate a MainActivity depending on authentication or certain features after allowing entry to the application.
Therefore, by allowing entry to MainActivity you end your previous screen (login or splash) with finish()
Example:
Intent intent = new Intent(Login.this, MyActivity.class);
startActivity(intent);
//finaliza Login.
finish();
You can add the AndroidManifest.xml attribute in your android:noHistory="true" file to the Activity that you do not want to be able to return to.
For example:
<activity android:name=".Login" android:noHistory="true"/>