This case :
https://smile.amazon.com/gp/product/B07VR3NXGF/ ... DOES NOT work AS IS, the case is a tad too narrow, too thin, and a bit longer than the Nova; and it's not very flexible at all. I'm thinking I might be able to cut out some plastic on the Apple Pencil holder side to make room for the Nova, but that might limit the cases ability to hold the Nova's stylus??
Very nice case though otherwise, wish I had an iPad Mini to put in it.
The seller also sent me an extra case, which kinda does work for the Nova, and looks like the following but with a different print (bright pink world map) :
https://smile.amazon.com/gp/product/B07Z1W3J28/
This second case works better for 2 reasons: 1) the outside magnetic flap holds it closed, but just barely (this case gets pushed out widthwise too, but fits the Nova perfectly lengthwise--probably not an iPad 4+5 compatible case); 2) it also has a dramatically more flexible plastic ... but the pen holder is external. : (

Both cases put the Nova Pro to sleep and woke it up just fine!

It appears that the Nova is really too thick for iPad Mini cases, but only by a hair; so a little modding or a flexible enough case might still work. I'm also guessing that the iPad Mini 2 or 3 cases would be the best option, as the 4 and 5 are a little longer, but then that wiggle room might be handy when the case distorts slightly to accommodate the Nova's width... I was hoping that was going to be what happened with the black case, but, again, it doesn't have soft enough plastic to accommodate the Nova's width AS IS.
I'm gonna MOD both these cases after playing with them a bit more tomorrow. I'll update later, and include photos of the changes if either works out.