For context and in appreciation to @stevenhoward's suggestion, here's a bit of additional feedback from our side: we managed to implement what we were looking for by following @stevenhoward's suggestion. Shortly, we're dynamically loading a model on top of the Simulated Scene. This isn't optimal for our use case (robotics), but leads to an scenario that allows us to continue moving forward with incremental prototypes to achieve our goal. Apple staff, it'd be great to get this capability implemented (switching the Simulated Scene) easily.

Thanks @stevenhoward, that's a creative suggestion indeed. Like the hack and I'll have our team test that out. I worry though that larger models may simply not "fit" within the museum. Forward looking, Apple folks, it'd be awesome to facilitate this out via a dev-option. I looked quickly into the files that ship within XCode 15 Beta and tried finding the models directly with no luck so far. 3D models seem embedded into databases so I'll probably have to do a binary search, which is going to take more time. Any hints from other devs would be welcome here.