I see now the thread above received substantial updates, with additional details on the use case and the interface.
Have you considered the creation of a stand-alone app that is independent of the wallet? It would make the platform more flexible and under your control, keeping the door open to additional wallets that may come in the future.
You can find some examples here: https://examples.near.org/
If you want to test by yourself how the NEAR Wallet login works, visit http://ref.finance/ and you will see how the apps can communicate after the login.