Okay – the things ya learn...
It turns out that if I want a good-quality monitor that's less than 24", I need to search for "portable" monitors. It turns out that there are quite an assortment of those available.
That 17.3" model I linked to above helped me tumble to that. And wow, you can get really high resolution small monitors ($$$). I've seen 15" and 17" "portable" monitors in 4k!!
So anyway, what I did is I ordered that 17.3" monitor and we'll see how it does. I found it someplace for $20 less than Amazon is getting for it, and verified that I can return it within 30 days if it doesn't do the trick, but I'm guessing that since I was ok with the 1080p 17" display on my laptop, that this is going to do the trick for me. The PPI comparison that
@krs provided above really tells the tale. I might someday spring for a 24" 4k monitor, but right now I have other priorities, including trading in this Mini for one of the new M2 models, or at minimum swap out the mechanical HD for an SSD.
I really appreciate everyone's input on this.