Sorry for you uncle.

If you have his email adress and access to password, its a starting point.

Now, to access the smartphones themselves, you will need the 4 number pin. At least in Portugal, mobile phones require a 4 digit pin to unlock when powered on. Then, finger print, pattern or face recognition to unlock and reach the “desktop” and icons and photos.

Mobile operators usually provide the 4 digit pin for the sim card, and they also provide a PUK number to insert after you insert an incorrect pin for a few times, usually 3.

So if you have the original boxes or smartphones documentation, search for the sim cards documentation with them. Take them to the operator store in person and ask them if they can unlock the smartphones.

Accessing the email, by resetting the password, may send a confirmation or code to one of those smartphones; but you will need them unlocked first. So first you should worry about unlocking the mobile phones, then, the emails.

I wish you best of luck!