Is it possible to use a stolen/found phone from 17 years old?

Question

Android

This topic has been popping up in conversation for a long time and wild disputes always begin. For example, let's take iPhone 7 on last iOS and Samsung S7 and S8 on Android 8/9, also on the latest possible update.
As they say to me: "there are craftsmen who will hack any phone. Both iPhones and androids can be forcibly reflashed and used." Of course, I don’t believe in this nonsense and answer that there is no way to break the iPhone at all, in any case it will ask for the password from the old account when entering a new one, BUT the fact of flashing is in question? Will Afonya on the last iOS do something with himself:
a) to an unscrupulous employee of the service center - this is what he is talking about, he has the opportunity to reset the password and account;
b) a hacker who can overwrite the pin code in the device's memory - I don't believe in it myself;
c) a phone repair engineer with hands, who can physically extract the memory and put a new one from alik - but here it's interesting.
Just if you have read this far, please answer point by point.
The same questions apply to galaxies. For example, S8 on Android 9 can really be hacked on the same points, does anyone know? And S7 on Android 8?
What do you generally think or know about the security of the latest smartphones? Is it possible to get pictures and something else, even if it is in a service center from a stolen smart phone?
Smart lock and "put a finger while sleeping" are not taken into account, we are simulating an abduction.
Possibility of use - when we enter our acc and use it as a new phone.
Another problem is that the phone can be turned off when stolen, or it will be with the Internet turned off, then he will not know in any way that he was stolen. Even if I block it remotely. Did the developers take this into account or not, what do you think?

Answer 1

As for the iPhone
Resoldering the memory module will not start in any case. Restore all data from the cloud when installing iOS.
A possible hacking option is to pick up a PIN, and this, by the way, is possible in recovery mode by brute force. There is no lock for wrong input.
Most often, the user makes a mistake by saving the authorization of the mail client on the smartphone to which the Apple ID is linked.
Any android is a bucket full of holes. Many hacking methods work even without flashing (google FRP).

• A. Yes, just a user error. Described above.
  
• B. It is possible to pick up a PIN code.
  
• V. He will install a new one, in any case, he will have to flash it using iTunes, he will also suck up the data of the old account along with the firmware.
  

Answer 2

Any Android on easy to reflash and use, infa from the phone xs, you can get it if the bootloader is unlocked.
It’s real to put an Iphone board or solder it, if without an acc, then it’s already more difficult to use it on easy with info.
Look at any phone on the 4pda forum for info and there will be a 100% way.