This is what I am most afraid of, knowingly or unknowingly got something installed that cause security problem.

iPhone are supposed to be very secure but I think their main security relies on control of what apps you can install onto your phone.

Among Android, Samsung is probably the most secure but they work different via Secure Folder. I using Samsung primarily because of this feature. It is basically a sandbox with both hardware and software protection. Being a sandbox, it is "cut" off from other part of the unfortunately infected phone.

So good idea to find any other Android phone with such feature.