Stolen iPhone/Apple ID/Device info

My iPhone XS Max was recently stolen overseas last weekend. I had the phone blocked and SIM card locked via my carrier almost as soon as it was stolen.

Back home now, I’ve changed my Apple ID password, am using a temp phone w same number and have marked it as stolen in Find my iPhone (the phone appears to be offline though).

Am I right in assuming my old iPhone is completely useless to the thief? And should I remove the device info from my Apple ID section? I’ve just received two Apple ID verification messages which I haven’t requested - is this person trying to log in to it?

Please help, first time this has happened.

Thank you.