Metadata insertion in azw3

My usual procedure:

1st) ePub file (starting)
2nd) Kindle Previewer (or kindlegen)
3rd) mobi file (intermediate, disposable)
3rd) KindleUnpack
4th) azw3 (final)

Is there any way to edit or insert metadata like type of document (ebook, personal document) or an ASIN in a azw3 file originated through this conversion route?
I'm on a Mac (High Sierra) and I'd like to be as far as possible from Calibre.

Thanks in advance.