steal their browser data. i haven't wiped my browser history in years, and that is just easy to search list of URLs dont need to be parsed out of some db blob (not something many anti-LGBTQ parents know how to / are going to do...). Steal their cookies and access their logged in social media accounts directly. Steal their saved passwords. Browse through the cached images and videos.
> Even then, we're still talking about a perfect surveillance engine
not even close. not going to beat this to a pulp but just to give you an idea, this does not scale well, not at all. are you going to look through 25 gb of photos? what if it's 90% cat pictures.