We used GodotEngine in the past when it was still called VRWorkout but had to switch to Unity due to business reasons.

The environment creator uses several off the shelf models under the hood with custom loras and blender at the end to create the exportable meshes.

Users usually need to workout in the game to achieve coins to generate environments because we have no actual monetization behind it, so we can't have people generate endless amounts of environments, but if you want to try it out send me a message at michael -at- xrworkout.io and I'll set you up so you can try it.