Yeah, exporting the same game with Construct 3 made it not work even on my Galaxy with 3GB of RAM, so I guess that export was using even more RAM, as suggested by that thread.
In case anybody else runs into this, I solved it by going through all images and cropping them. Did save quite a bit and now it runs on iPhone 6 and 7, where it was crashing before.
Just to clarify this is not the actual mobile app, this is HTML 5 export running on mobiles.
So if your game is over 500 MB in RAM ( according to debugger ) and crashes on mobiles, check that first. Error you get doesn't really tell you anything other than the obvious which is that something went wrong