Hi @acasio,
Thanks for the question!
Please see the "Specification Divergences" section of our ACME v2 announcement post:
The “ready” state on order objects is not implemented. Orders remain “pending” when associated authorizations are all valid and finalization may occur. Client developers should check the authorization statuses to determine if the order is ready.
You should POST the finalization URL when the authorizations are all valid, even if the order remains "pending".
We've added the ready state to Boulder but haven't deployed the change yet as it breaks some popular ACME clients (notably Certbot).