Re: "How to keep Accessibility zoom picture-in-picture window stationary and not follow the cursor?"
Sorry I'm no expert in this area, yet your question certainly deserves some response.
Apple support have an article online (link below) that may be helpful.
First: in checking what settings you have in place now,
and
Second: in checking what changes are currently possible to make.
See how to: Change Zoom advanced options for accessibility on Mac - Apple Support
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Re: "Is there a way to get the Accessibility > Zoom Picture-In-Picture Window to?
- Stay stationary
- NOT follow the Cursor
I want to set the Picture-In-Picture dimensions, lock it in place, and then be able to move the mouse anywhere outside of the that window, but have the window continue to display ONLY what is under the borders of the Zoom Window."
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To help get started with the settings a few excerpts from the above article are pasted below.
It may be worthwhile to explore all the options (ie: either in the iPad settings:or in the linked article)
Seems there is much to assist and allow you to take control
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Above linked article says:
"To change these settings, choose Apple menu 
> System Settings, click Accessibility 
in the sidebar, click Zoom,
then click Advanced. (You may need to scroll down.)
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Appearance Options:
Keep picture-in-picture window stationary = Keep the zoom window in one location on the screen.
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Controls options:
Use keyboard shortcuts to adjust zoom window
Change the size and position of the zoom window while using the indicated keyboard shortcuts."
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Follow Focus options
"Follow keyboard focus"
Magnify the area of the screen that has the keyboard focus:
* all the time,
* just when typing
* or never.
As well as other "Appearance", "Control", and "Follow Focus", settings besides the above:
There are also settings options for "Shortcuts" or "Modifiers for Temporary Actions" if you wish to use them.
ie: See the above linked article for the full details.
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if needed:
For more support, or assistance from the experts:
see: How to contact Apple for help with accessibility features - Apple Support
