I would also say, a small phone is a great opportunity to add whatever features are necessary to offload usage to a watch (Bt,BtLE), car, smart home (UWB), smart glasses, ear buds. This seemed to be the way Essential was going. I would love the ability to hear my texts, either in ear buds or smart home, and hold my phones power button like a walky talky to dictate responses, almost like Android Auto. (Maybe even a knurled physical dictation button on the rail right next to where the gboard microphone soft button is located). And have UWB smart appliances know I was approaching and 1-factor authenticate me. All this to say, don't skimp on the innards which can help the device grow with accessories. I think accessories are really where a manufacturer can win. Where your phone just becomes a remote so all your other devices know it's you.
And when you are looking at the phone and using it, it needs to be weighted (battery down?) at the bottom so it balances in the hand better, a la Palm Pre (I so wish I had bought one instead of waiting for a second generation). No more pop-sockets!
I also suspect that narrower is more important than shorter. And thicker is better for battery and the bend test. Remember when Pixel 1 had an angle to its back? Imagine a phone that can lay firmly on a flat surface on slight angle, just enough to go into portrait or landscape mode, and not wobble. And if the speaker were on the back, it could use the flat surface to reflect the sound back at the viewer. (I think rog or another had an angled phone back that looked like broken glass).