how to display metadata in the browser

The easy way for a feature request is the feedback form: The developers will read it, but you may not receive a reply.

Apple - Photos - Feedback

If you want to submit a feature request as a usability problem, you may want to use the Developer Bug Reporter. But that is a lot of work, see: Detailed and Effective Bug Reporting | Apple Support Communities

I am using PowerPhotos as a second Browser for my Photos Library. Even the free Trial Version of PowerPhotos lets you view the Photos Library with titles and subtitles below the thumbnails, and you can also see a list view with the metadata arranged in columns. I simply keep p PowerPhotos open all the time, because it needs a few minutes to launch on a large library. But in list view I can sort the photos by many different metadata:

You cannot sort by file type in Photos, only search by file type.

But if you download the free trial of PowerPhotos you can view any Photos Library in list view and sort the items by man criteria by clicking the headers of the columns in list view, for example by file kind. You select the columns to be displayed in the View menu:

https://www.fatcatsoftware.com/powerphotos/Docs/index.html

And PowerPhotos can me directly back to the photo in Photos, if I want to edit it.

The only metadata you can display in the browser are the title and badge overlays.

Enable "View > Metadata > Titles". Then the title of the photo will be shown below the thumbnail. Other metadata can be added as badges.

The handling of metadata is still sadly lacking in Photos. I hope the next versions will add a bit more power to handle Metadata. It is a far cry from what we could do in Aperture.