In Android, if an app wants to run in the background, it usually needs to create a service that runs in the background (and/or after boot is completed). So, if the app wants to listen to the microphone all the time, it needs to run such a service from my understanding, and in the modern Android version, they are forced to create a notification and it needs to clearly specify what it does in the notification or it will violate Play Stalkerware Policy which Google Assistant does not show it.
How can this be allowed? Also, how can an app implement a microphone listener if Google Assistant is already running?