Microsoft Photos doesn't seem to want to open a photo, it thinks I don't have any

I just want to navigate to a photo anywhere on my PC and edit it and see what the editor looks like, see what it can do. Like you can do in any other photo editing program in the world. Microsoft Photos (non-legacy) doesn't seem to want to do that.

When I click on the Gallery, it shows me this:

If I click on the PC icon there on the left, I get this, despite having many thousands of photos local to my PC:

I have a connected USB drive with 60GB of photos on it so I go there via the import button, hoping to navigate to an image that I'll select and it starts counting videos and images like crazy and showing thumbnails. I don't see why it can't just show me an explorer view. It doesn't offer me the chance to filter by filetype or sub-folder level. So instead I just have to wait while it goes through 60GB and makes tens of thousands of thumbnails. Why?

I just want to open one image. Eventually it stops and I select an image and click Add 1 item. I don't know why I'm having to "Add 1 item", I'd just like to open it. But it seems that it wants me to copy any image from that drive so that it becomes "a local photo". Not the way Microsoft applications traditionally work but OK.

So I click on "Add 1 item" and I'm faced with the following screen. It wants me to choose a folder (there are none to choose from) or create a folder (that button is greyed out and unselectable as is the Import button). I'm left with one option now, to Cancel.

What an awesome application there Microsoft. I guess I'll stick with PhotoShop. It has an explorer style open dialog that can open a file from anywhere and a similar for saving.