"Pending" means that the phone does not have an Internet connection. There are several reasons for this:
The battery has run down
The phone cannot connect to Wi-Fi where it is located
The thief has wrapped aluminum foil around the phone or has placed it in a Faraday Bag to prevent the phone from receiving a signal or transmitting a signal about is location
If the status of the phone has been "Pending" for a week or more, there is about a zero chance that the phone will ever come back online. You will never see the phone again. It is gone.
That being the case, it would make sense for you to try to erase the phone, but do not remove it from the list of devices that are using your Apple ID.
It is unfortunate that you have received incorrect from the police. Believe them if you wish, but none of the experts on this site will agree with the information that you received from the "police".
Be extremely careful if you receive a message from "Apple" or "Apple Support" indicating that your phone has been found.....and you just need to provide some personal information so that the phone can be returned to you. Any message like this is a scam that is trying to trick you into providing your Apple account details, so the bad guys can access the data on your phone.
Apple will never send a message like this....because they do not get involved with lost or stolen phones....so you know that the message is not from Apple.