I understand. Think about the logic of how this is set up and you can configure it to your needs.
In my video, I have a group already created, however, if you follow the API docs, you can create a new subscriber group for the “areas”.
So that when a user sets their location, you can create a new subscriber group or add them to a subscriber group for that area with this documentation on how to add a subscriber to a list.
Then, you can create a campaign and send it to that specified group when a new job becomes available.