UPDATE: I've been looking into the MessageInputContext file and came to the conclusion that imageUploads are done via mapping through the selected images returned from the promise from the image picker, with the action of uploadImage which does a channel.sendMessage (if the doImageUploadRequest/doFileUploadRequest functions aren't defined in the Channel). I presume that this would mean that each individual image/file just needs to be 100 MB's or less for this to work. Interesting, wondering how the images are rendered in a group in the widget. Presume there's a check to see how many assets are uploaded to render multiple tile gallery widgets.