Enforce ISO standards when creating/editing customers portal account

Problem

The customer is allowed to complete their account details page with free form text in the postal code form:

account_form_standards

When they try to make a purchase, they get an error about their state, but I believe the problem is actually about the postal code they've provided:

Screen_Shot_2020-03-30_at_11.16.44_AM

Reported example: https://gitlab.zendesk.com/agent/tickets/151819

Proposal

Enforce standards when they create their account so that the system doesn't present an error when they are trying to make a purchase.