safe

You did the right thing. Your Mac cannot be used, and is effectively a brick unless and until that password is provided.

For reference: If your Mac is lost or stolen - Apple Support. Confirm you followed those steps.

Did you turn on the Find my Mac function?

Did you call AppleCare and the police and report the serial number as stolen?

Short of that, there isn't much you can do now that it is stolen. Unless you have some idea where it last was located, you are probably better off looking into making an insurance claim for where it was stolen, and see what you can do to get another Mac of similar age so you can recover the information from a backup.

Macs will not run an OS older than shipped with them.