James Do you still have to go through a process to declare your account?
Belgish law seems unchanged in this regard from what I told you last year: https://together.bunq.com/d/35297/4 Right now bunq only offers Local IBANs for Germany, France and Spain. Is your question about a hypothetical Belgish IBAN being offered by bunq in the future?
And would it be as a local or foreign account?
According to bunq, all their bank accounts are Dutch bank accounts irregardless of what country's IBAN is used. That would mean if you live in The Netherlands, they would be domestic accounts. And if you live in any other country, they would be foreign accounts.
Quote from Terms of Service:
When you open an account with us, you will be entering into an agreement with bunq B.V., a Dutch financial institution, and not with any of our foreign branches. This means you will have a Dutch account, regulated by Dutch law, regardless if a non-Dutch International Bank Account Number (IBAN) is linked to your account.