There does not appear to be a way to change the tone on an iPhone for the Google home app when a camera detects something critical such as an unfamiliar person that has entered your home while sleeping. Critical miss almost rendering the technology obsolete. Does Google intend on fixing or due to safety/security concerns at this time the Google home app will not be a good solution for home security?
We appreciate your interest however, we don't have any news to share about changing the notification sound for your Google Home app when your camera detects an unfamiliar person. We're always looking for ways to improve and we'll take it as feedback.
I also suggest that you send feedback by following this link. Let me know if you have other questions or concerns, otherwise I’ll be locking this thread after 24 hours.