I'm still on a Z3 compact (4.6" screen, 5" total height) which I use single-handed quite a bit. Decided I would never buy a phone above 5" size, with 4.6~4.7" being my ideal preference.
My hands are (to my knowledge) average size, maybe a slight bit on the small side.
Really wish more vendors made high-end smartphones below 5"... (I previously used a Z1 compact, and before that a Nexus 4 - loved both.)
FWIW 5" bezel-less screens can fit into the same space as a traditional 4.7" phone. Just nobody is willing to make a phone that small any more. You really need to shop by outer dimensions rather than the actual screen size now.
I do look at outer dimensions and at weight. I try to stay under 130 mm and around 130 g. Very few decent phones are there. The SE for iOS and basically only the Sony Compact line for Android. But the latest model weighs more than 160 g and I can't understand what those extra 30 g are for.
I encourage you to stick to your guns on this. I used to have a Nexus 5X (which was a hair too big), and moved to a Moto x4. The x4 is basically the exact same size as the 5X, but they went with a "fancy" design for it with metal construction and a glass back. It's much heavier than my previous phone and it's slippery because of the glass construction.
It's borderline impossible to use with one hand, and hard to avoid dropping occasionally because it's so much heavier and harder to grasp. It's so slick that it regularly slides off of almost flat surfaces.
My next phone will be 5" or less. I have the same size preferences as you, and also owned a Nexus 4. I still think it was the pinnacle of the cell phone form factor.
I bought a "Love Handle" (https://www.lovehandle.com/) at a concert merch booth and have been using it ever since. It's thin enough that wireless charging still works, and much easier to get out of a pocket.
I think that you have the numbers mixed up, every source I have checked (including the Sony website and an actual device in my hands) had the XZ2 Compact at 135 mm in the longest dimension. The tall, narrow XZ2c is about as wide as older Xperia Compacts, but noticeably taller.
PS: additionally, I'm actually not all that happy with "better" screen to body ratios, coming to the XZ2c from the original Z1c. Accidental touch events from the holding palm at the screen edges are a daily nuisance for me.
Not great. The new models (PopGrips) advertise themselves as supporting it, because they're easy to remove with a twist (which defeats the convenience of wireless charging.) I still use it but 1) my popsocket is mounted flush with the bottom of my case, 2) it only works conveniently on a vertical charger[1], as they're narrower than flat pads[2] and 3) the phone has to lie horizontal so the PopSocket hangs off the back.
I did just test it vertically and it seemed to work if the PopSocket itself hung onto the lip of the charger. I think this might affect the charge rate, though, due to the distance from the coils.
My hands are (to my knowledge) average size, maybe a slight bit on the small side.
Really wish more vendors made high-end smartphones below 5"... (I previously used a Z1 compact, and before that a Nexus 4 - loved both.)