Firebase: Can I prevent multiple login of same user?

MIT App Inventor Help
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1

I want the user to be logged in only from one device / instance at a time.
I am using firebase authorisation to log in. (Mirxtrems extension) as used by TIMAI2 in his tutorial "How to have Secure Rules on Firebase, and allow Auth Users to Read/Write"

So, if the user is "in session" from device a, they should not be able to log in from any other device.

Any leads how to use '" Authentication State Persistence". Any examples?

Much appreciated in advance.

2

Google gave me this (read it all), it is complicated !

This is a peculiarity of Firebase, but not sure what difference it makes, can you give specific examples of why this might cause a problem with an App Inventor app ?