During the interview he promoted a new book, his brutally honest and funny memoir.
So this is a noun phrase in apposition, but is that what defines it as a noun phrase in this example (being in apposition)?
I would have thought 'a brutally honest and funny memoir' would be a noun phrase, as there is no subject.
He just stood there, his face clearly revealing his disappointment.
This is an absolute phrase, but has a subject like the first example but contains a non-finite structure.
So other than that and their difference in usage here, they are similar: his memoir/his face.