Why Australians are snubbing this fast and free way to lodge their tax returns
They give you a to-do list of all the tax years you need to file.
[Android][App] Obtainium. Get Android App Updates Directly From the Source.
They don’t seem like they have background installation mechanism right?
From the readme on GitHub:
Auto (unattended) updates are unsupported due to a lack of any capable Flutter plugin.
Usage of only Microsoft Authenticator?
If it's restricted to MS Authenticator it's very likely push notifications.