Succinct and well written draft. It's ready. My only suggestion is adding a little more into the iana considerations section. Something like:

"There are no IANA actions in this document, only a clarification. [RFC7470] defines the Enterprise Numbers allocated by IANA and managed through an IANA registry [RFC2578]. This document clarifies the Private Enterprise Numbers (PEN) as described in the IANA registry."

And/or re-word the iana description up in section 3. That second sentence "This document further clarifies that what the IANA registry described is the Private Enterprise Numbers (PEN), in which registrations and the registration location are further described by [RFC9371]." is awkward to me. Would this say the same thing?:

"This document clarifies the Private Enterprise Numbers (PEN), as described in the IANA registry. The registrations, and the registration location, are further described by [RFC9371]."