As it seems to have gone unremarked on these forums I would just like to say that as of v1.1.4 of ARV iOS the max canvas size you can now make is 6000px x 6000px!
So a high quality A3 print is well within that pixel range and quite possibly an A2 print as well
(Not having an Android device I can’t say if the same now also applies to that version of the mobile app too...)