With that in mind, a battery health tool is probably the fastest way to tell how old a phone is going to feel. Otherwise nothing else is going to suffer wear and tear. If the phone is in good shape, and the specs are agreeable, then it doesn’t matter how old it is.
Hey there, I’m not sure I understand what you mean by “first activated”. In general, you activate a SIM card, not a phone. This would be associated with your current phone plan, not the device itself. Your carrier would be able to provide that info. If you’re referring to when your phone was first purchased/turned on, then most folks tend to add their Google account during setup, which might be why there’s a suggestion to check your Google account to see when the device was added.
The IMEI is potentially useful as it’s a device identifier, but generally doesn’t matter to anyone except your carrier.
It’s a bit difficult in a case like this, as it does add context and acknowledges their new identity so as to link what was a well known video to an existing person. I’d struggle to know who this was otherwise. I don’t think there’s any malintent here.