Suppose you have a stalker and this person has access to professional advice.
Suppose your Android phone was hacked by means of physical access, i.e. known unlock pattern or stolen password note, with malicious software either commercial or of unknown customisation grade.
Suppose anti-virus scans are clean.
Suppose there is no data on whether the Play Protect had been turned off or the "Downloading from untrusted source" had been enabled.
Suppose there aren't any Running Services or hidden Apps that can be identified as masked stalkerware apps with the help of Google.
Suppose the phone is not rooted. But the scope of infection of system partitions is unknown.
What would be some methods to detect the hack? For example, will forensic investigation of device images be of use? Will the Mobile Verification Toolkit be able to detect something more than the anti-virus scans? Is there anything else?
Most tutorials only list the most known DIY and/or GUI based malware detection techniques.