Hello really like your game:) and I really want to use the same plugin in unity that you used for this project can you please explain how you did this and which version you used?
The plugin I have used is the Google Cardboard XR Plugin from this link to make this possible. I used a Baldi's Basics decompile which you can get here. I also used Unity 2022.3, but you can use any Unity version you want.