The updates contained in draft-ietf-anima-constrained-voucher are important for both security and to align with other protocols updates and trends (e.g. SNI in TLS). The security considerations in section 15 are well detailed covering identity, root of trust and allowances for looser restrictions are justified for a self-signed certificate, UDP/DTLS, use of a localized protocol to limit the scope of response to the immediate network, and justification for a constrained protocol (CoAP) for communication is well considered. 

The work builds on several other protocols and represents some important and well considered updates.

Best regards,
Kathleen