Thinking of buying a used iPhone and MacBook. Probably an iPhone 7/8/X and MBP 2015. As a security conscious (many would say overly paranoid) person I'm considering the risks. I'm quite sure I'm not someone specifically targeted by state-sponsored hackers or anything like that.
What security risks would I face and how do I mitigate them? Would a factory reset of an iPhone be sufficient to rid it of anything the previous owner might have had on the phone - malware perhaps? For the MBP I'm thinking just replacing the storage drive with a new one, but not sure about firmware level malware.