Well, that sure was easy, and I certainly had missed it.  This selection does indeed produce the behavior I was hoping for; thanks so much for the help!

PR

On Thu, Aug 29, 2019 at 12:17 PM Jack Kamm <jackkamm@gmail.com> wrote:
> Is there any way to just open my org-agenda-todo items in the /current/
> window, or even just any window that already happens to be open, without
> modifying, splitting, or above all deleting any others?

Does customizing the variable org-agenda-window-setup (e.g. by setting
it to 'current-window) solve this?