Yes there is an A0 version with the blouse pattern I downloaded. It is 3 A0 pages though. I'm sure Stylearc would have got a blouse pattern onto 2 A0s. Still, don't look a gift pattern in the mouth!
Actually, I don't find 40 or so A4 pages too bad. I recently pieced together 100+ A4 pages from a Butterick pattern (no A0 option) - now that was too much!