[rchaud]

Nearly impossible, and I'm saying this as a lifetime Android user.

Your best bet would be boutique OEMs like Unihertz, who have a 3.1-inch Jelly phone (underpowered) and a Blackberry style Titan Pocket with a hardware keyboard and 4-inch screen.

Neither of these sound like what you want. In the Android world, one can only hope that another small-time OEM will swoop in to fill the gap, before inevitably disappearing.

[fragmede]

Since pocketability is a large component of the size question, the foldable Motorola Android phone is worth taking looking at (if you can afford it). Unfolded it's modern-sized but folded up it fits in more places.

[frosted-flakes]

It's the other way around for me. Usability trumps everything. Trying to use my phone one-handed is extremely frustrating, even with a rear grip, and I have what is considered a "small" phone (Samsung Galaxy S10e).

I wish phones had thumb trackpads like BlackBerry phones had. The BlackBerry Classic (2014) had one and it worked incredibly well, even in Android apps, surprisingly (it works by moving the focus, not a mouse pointer, except in the browser, where the pointer means desktop mode is actually usable). Being able to reach the entire screen just by twitching your thumb a few millimetres is sadly probably never going to be possible again.