How can I verify if a Macbook was reported lost or stolen?

If your Mac is lost or stolen

When I find things left behind, or stolen and abandoned too I guess, I take it to the concern's lost and found. If no L&F, I take it to the police. Credit & debit cards I've found I've dropped into the bank's night deposit or sent it to a teller via the drive up system.

I'm not an investigator, so I turn things overr to what seems like the appropriate location based on what it is.

I don't think serial number by itself is going to be of any use.