Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
I am afraid no one can provide ways to go around regional availability issue.
But if you have a perpetual copy of Office that contains Publisher, it can still run and work, it just won't receive updates anymore. If you are using a subscription, then the app will not work anymore.
Otherwise, you can consider third party options like Affinity or Canva.