From the DNS Directorate perspective, this document has very little impact.  Its main reason for existence is to formalize the entry of "co", for CoAP over DTLS, in the TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs registry.  It is already assigned per expert review, this just gives it an official RFC.

The DNS relevance is with the SVCB and HTTPS records, which reference the ALPN registry via the alpn= parameter.

The document is straightforward with no noteworthy issues.