> There are more steps you can take to ensure greater safety.
There are firmware infections that can persist even after hard drive format. Though to my understanding os/user space to firmware infections are rare. As far as I know a 'factory reset' on phone and some laptops does not reinstall firmware and clear out firmware infections. So to my understanding the 'factory reset' found on phones is analogous to formatting your hard drive, reinstall the os, software, and data required for your use.