If I remember correctly you can just specify which axis is up on exporting with Blender; that's probably the best choice here.

You can create this in code instead of storyboard for sure, the only issue is macOS and iOS have different initialisers for ARView. When doing this previously, I just used an #if os(macOS) or similar to determine which one I'm using, and I get the exact same scene displayed on iOS and macOS.