Okay, so apparently I missed the update to Amazon’s Kindle for PC, despite my application settings. News: you can now highlight and make notes. (If you also missed the update, you can download the new version over the old one.) This is somewhat tedious to do vocally, because you need the Mouse Grid and mouse movement and dragging commands for every step, but it can be done.
When you stop dragging the cursor over the text you want to highlight or annotate, a context menu gives you the choice of highlighting or adding a note with your highlight. Move the mouse cursor to the option you want and click. A panel will appear, in which you can dictate your note. However, PLEASE NOTE: selecting or correcting words while annotating is a little dodgy. Your cursor might not return to the right place. Also, if you want to edit your note later on by clicking the Edit button that appears in the pane when you mouse over it, you can’t vocally correct or select individual words at all. You have to give the “select all” command and either say “backspace” or dictate over your selection.
At this point, even despite Amazon’s keyboard shortcuts, I think I would prefer reading via Foxit. But Amazon does have a wider variety of books, so I think for some things we might just have to make do.