I’m looking for something much more minimal than what I’m currently finding. Just a pure white theme, left sidebar with simple text column menu. Main content, on the right, a large photo image browser; that is, one very large photo displayed at a time, click on it and/or arrow to go to next image. A slideshow, but without effect, bullets, thumbnails, etc.
Something truly minimal, not “minimal.” Here’s an example of the type of thing I’m looking for (not looking for exact match, but this basic idea).
What you are describing can be custom coded by a skilled WP dev in a few hours. I am pretty sure there are plenty of themes which could be customized to look like that, you are just mislead by their previews which do not show exactly what you have in mind. But everything can be customized, especially when you want to just remove features.
For example Twenty Fifteen looks exactly like what you need:
You just need to change that grey BG color to white, which if can’t be changed directly in the admin, is like one line of CSS code, and then find some 3rd party gallery plugin which will go into the page content (if the built-in gallery which you can create using the default block editor is not enough for you).
The theme which will 100% fit your requirements out of the box probably doesn’t exists, but I am sure there are plenty of themes which can be easily customized to work like that. You just need to think little bit outside of the box.