Hi,
Just to understand what would be suitable for you, I guess the simplest starting point should be the Samsung S7 from /e/ (5.1" 16:9; overall, quite widely available devices you might have seen / tested if they suit your needs): would it be too big?
Have you considered getting one of the refurbished phones that /e/ is currently selling with their OS preinstalled? I believe the S7 meets your criteria, although I’d advise reading through the forums first to confirm any known issues (it’s officially supported anyway):
Samsung’s Galaxy S7 and S7 Edge are also very widely used and popular devices in my country. But just as often I see shattered glass on the front and back after it has fallen down. If I had to operate a phone with one hand and the risks involved, my main focus would be on a very robust device.
The good old Samsung Galaxy S5 (e-0.7-p-) with an outdoor rugged bumper case is not necessarily an optical highlight, but it can survive a slight height and it’s enough for my everyday smartphone life.
Another aspect: The most sustainable phone is the one you already own
I was looking for precisely this and settled on the Samsung Galaxy A3 (2016). Good experiences so far!
@Manuekris
Of compact devices that are up-to-date with cutting edge technologies I only know two: Sony Xperia XZ2 Compact and Sharp Aquos R2 Compact. I didn’t go for the Xperia because I read too many reports of defective displays. I didn’t go for Aquos because I wasn’t determined enough to go through all the hassle of getting what then was (and still probably is) officially available on the Japanese market only. I settled for Samsung Galaxy A3 (2017, so not officially supported with /e/, but I have LineageOS on it), which was next to perfect for my needs but unfortunately the camera was far below what I consider decent and after a few months I traded off on the size and replaced it with Galaxy S9. So far so good. If I were you, I’d have a look at the two Xperias listed as supported devices here. 5.2" is not far from your initial requirement. HTH.
Thank you all! I think I will buy a s7 refurbished…
Take a look to this topic :
OneDevice looks •very• interesting to me!
How about the Samsung s4 mini? I was looking too for a small phone and went for this. Can’t say about performance because I am facing problems with network S4mini I9195 serranoltexx no mobile network
I like this thread!!!
Compact Smartphone? Try this.
I don’t know if /e/ works on it 
Check out this thread as well!
What about this?
Funny little phone. Not sure how everyday user experience will be on that small screen (typing, reading).
I use the predecessor “Jelly Pro” daily since years, a long time as my main phone, now mostly as a music player and secondary phone. Typing works flawlessly with a swyping. Screen resolution isn’t good, don’t would use it as an e-reader. Screen big enough for messengers, tan apps, music players and some games.
Battery is very small but exchangeable ( think not any more on jelly 2) and two sim cards and micro SD simultaneously. Really love it.
In a pocket it feels like carrying a “big” lighter.
I think the new screen and bigger battery on the jelly 2 makes it a super usable device. Without a jelly Pro I would definitely get a Jelly 2. The fixed the two most important things, more then doubled the battery and twice of the screen resolution.
I preordered the Jelly 2 yesterday.
I plan to use it as a secondary phone for travel as the Pocophone F1 is far too big to carry it in your pocket for several hours.
I really hope there will be /e/ for the Jelly 2.
You obviously have good eyesight! 
Cool, never used swyping, I guess it takes time but works well after a while.
Theres basically only compact phones with e. Good luck trying to find a big phone with e (hint: its just two!)