Not one thing wrong with that, have one. You plug an ICSP board
into the connector provided and it seems to work.
No different that doing same with a Uno and ICSP or Nano with ICSP.
However its NOT the same as programming a Arduino with boot.
Yes docs are sorta a big thing but its in the "Arduino Ecosphere"
so it is there if by indirection. Its annoying but that is geekery.
Please reply on list so we can share.
Off list email goes to trash, I had to due to scrapers.