I always hate how most VAM environments/assets have bad looking or no shadows when you place lights in the scene. You're environments are truly one of the best available for VAM and correctly work with custom placed lights without having to use UnityAssetVamifier. The materials work correctly and the specular detail isn't lost since I don't have to use UnityAssetVamifier.
I've tried bringing assets from the Unity Asset Store or Sketchfab into VAM myself, but it hasn't been easy because you can apparently only use an older Unity version. So it might be best to just leave this up to the professionals lol.
I saw you mentioning that people don't leave many reviews. I usually don't leave reviews, but it should be known that you're environments are really top tier man :)
Thank you!