In stock Android, a .nomedia file in a folder tells the media scanning service to ignore this folder and it's subfolders. This is very useful when an app wants to store files in world readable file systems (like the /sdcard partition), but not have those files appear in apps like Gallery.
I think it would be wise for Oculus Go to adopt this convention in their Gallery app at least or it could be increasingly difficult to locate relevant media files amidst a sea of thumbnails and temporary images.
Although it's been part of Android for ages (since 4.0 perhaps?), I can't find any official documentation. Here's a reference: https://lifehacker.com/5793803/disable-media-scanning-in-specific-android-directories-by-creating-a-nomedia-file