Blueprint assignment location

Question

Dear all,
I'm trying to do what I have already done for resource and resource group location, limiting them to a subset of locations and offering a default value at the time the blueprint is assigned, what I did not find the way yet, is how to manage the locations for the assignment: a default value and a list which includes only certain values and not the full Azure locations list.

To clarify, here you have the section when you start a blueprint assignment from the portal:

Answer 1

You cannot restrict the region a blueprint is assigned to, through the blueprint its self. At the point you are setting this up the blueprint has not been run, so it can't provide this sort of restriction.
You could create an Azure Policy that restricts where a user can store resources, but this would be outside of your blueprint.