Admittedly, these forums will likely not yield many suggestions for specific app recommendations (they are much more geared towards developers and working with the underlying technologies). That said, there are two things that stand out in my mind that might satisfy your goal.
One thing to consider is that iOS/iPadOS already includes technology to view 3D/AR objects in “space” (rather, the “real world”), by way of the AR Quick Look technology. This technology supports allowing users to open 3D/AR objects in the .usdz or .reality file format, without the need for an app at all (those .usdz or .reality files could be provided to a user through AirDrop, Mail, Messages, or viewed directly from a link to a file in Safari). The
Quick Look Gallery has some great samples of files you can view on your iOS/iPadOS device, to get an idea of how easy it is to view AR content accordingly. AR Quick Look leverages many underlying AR technologies (such as object occlusion, person occlusion, realistic lighting, etc.) that makes the content appear truly in the real world space.
Adding to that, as you mentioned art in your post, you may have desire to have scenarios where users can view art as it would appear on a wall in their home; this would mean some technology would need to detect a vertical surface, then apply the 3D/AR art object to that space, again, making it appear as though it is truly there. AR Quick Look has the capability to do this, when working with .reality files. I would suggest having a look at Reality Composer, which you can learn more about in the
Creating 3D Content with Reality Composer documentation. Reality Composer would allow you to create an AR experience that anchors your 3D/AR content to a vertical surface, would allow you to import your 3D/AR art object into Reality Composer to preview it in the real world, then export your experience as a .reality file that could be provided to a user, which they could view on an iOS/iPadOS device without an app. Reality Composer is available from Apple in the App Store for iOS/iPadOS, and is included with Xcode for macOS.
