@Olo I think some of those above are from a special CD-ROM that came with some edition (mid-90s and CDROMS where all the rage back then). My old French copy had more, like this one :
manara.jpg
Furthermore, in 2018 the Italian newspaper Corriere della Sera published Manara’s comics integral work in a special “Artist collection”. For this event, the artist remade 45 new original drawings to be the new covers for each of his albums.
Here’s the one he did for Gulliveriana :
manara_2.jpg
If he’s not “one of us”, he definitely has some innate giant/tiny sensibilities.