Thank you @Catherine - the long tap option seems like it would be a really great workaround for this issue, I'll give it a try when I get the time.

As far as real-estate for placing a control button the focus screen, I was thinking more on the lines of adding a 5th tab (there's room up there ...

Another observation: I can manually change focus and take individual images with the Tamron lens. While not optimal, it is a workaround, and the " Focused " checkbox, accessed in Live View is a help.
A nice feature for the Android app would be to have a " Take Picture " button also on the Focus tab ...

An update:

I can create a successful stack using my Nikon 35mm f1.8 lens with an extension tube... I'm also experiencing the lens shift that @bigzero2201 describes in their post, when shifting between points A & B and using my Tamron lens.

This is wildly disappointing, while I'm sure that it's a ...

Camera: Nikon D7200
Lens: Tamron 90mm F2.8 macro
Tethered (USB) to Pixel 3xl

Hi:
I can set A & B points, and see the extent of the focus between them, by pressing A or B buttons, but when I perform "Start Shooting", I end-up with many identical images: in-other words, my cameras focus isn't being ...