That is in interesting question!
Just checked this one for any Bianchi identifiation on the frame, none.
PXL_20230127_132501638 on Flickr
The only indications are the paint, which is original, and the stampings of numbers and letters. Oh and the obvious integrated head set which I think may be unique for late 60s and , '70 &71, maybe 72 Bianchi's. This one has been identified as a '71.
I added the decals which were provided with the frame set.