Retrieving saved games, etc. from removed Xbox One hard drive

Unfortunately you would still need his account information in order to properly use any of the save data on the new console as he would still need to be able to sign into his account. As already stated, if he was signed in while playing, his saves would
have been stored on the cloud and not the hard drive, so the hard drive would only have the game files which can be redownloaded once he signs into his account.

The internal hard drives on the Xbox Ones are not meant to be removed and swapped and the Xbox files are not meant to be seen on a PC. There would be no way for you to recover the files on his hard drive without breaking the terms of service and risking
banishment. As such, that cannot be discussed on the forums.

Hi! if you played with your console connected to the internet, usually saves are also stored on the cloud. You just have to start the game with the account that played and it should sync the save automatically. If you don't remember the email, you can
try to recover it https://support.xbox.com/en-US/my-account/microsoft-account/forgot-microsoft-account-solution

Does he not have any screenshots on his phone or other social media that will show the email address? I know it's a long shot but I have pics that show mine when I have taken a pic of my gamerscore for example from my dashboard.

His saves are saved in the cloud in his profile, the ideal would be to remember this email.

That would be ideal, but I've had no luck getting him to remember.

Hi! if you played with your console connected to the internet, usually saves are also stored on the cloud. You just have to start the game with the account that played and it should sync the save automatically. If you don't remember the email, you
can try to recover it https://support.xbox.com/en-US/my-account/microsoft-account/forgot-microsoft-account-solution

I already tried that method. We thought we figured out the most likely email address, but the password reset didn't work. It stated we didn't have enough information to prove it was him. When he set this up his account he was 10 or 11 so he doesn't remember.
Who knows what information he put in to identify himself?

That's why I'm trying to find a method to recover all this information from the original drive, preferably without having to install the drive into the new Xbox.