It seems like that's basically the approach they're already taking. Items such as these read like plausible fake data:

> Your timezone is reported to be UTC

> Not all fonts installed on your computer are available to webpages

> Your browser reports a specific, common version number and operating system

> The Media Statistics Web API reports misleading information

A user with that particular combination of settings is very likely to be running with fingerprinting resistance enabled. Your parent is hoping for something where the site is unable to tell whether the feature is enabled.

Librewolf does this. It's a patchset for Firefox that removes all the bad stuff and makes a bunch of security/tracking improvements. It fakes your agent, timezone, screen resolution, disables a bunch of APIs that can be used to track you, etc.

It _does_ break some websites, but I just use another browser for those one-offs.