Apple Photos catalogs are proprietary Mac-only file formats that can contain hundreds of thousands of images, thumbnails, and sub folders. Bridge is showing you exactly what it should because it lets you browse what is available at the OS level.
If you want to see what’s inside the catalog you’ll have to extract the content first.
Also, Apple Photos doesn’t support industry best practices of embedding metadata in the images. The only way to embed metadata with Apple Photos is by exporting images OUT of their ecosystem, and when you do that the file size are typically increased significantly or compressed significantly.
If you want to embed industry-standard metadata the workflow I use is to extract photos from the Apple Photos library and use other software and keep the files available in the native file system instead of keeping them in a proprietary catalog.