Two years ago, with Atom, I've found MessageEasy keyboard the best for small screen size. The most recent update, for a reason, is available only from their web site for side loading, but I had no problems even with the version from Play Market.
Regarding WiFi, please note that Jelly 2 will not connect to channels 32-48! Actually, Unihertz support recommends channels 52-128, though 160 worked for me just fine. So, for a stable setup, it requires manual channel selection at the router.
Fingerprint scanner works much better with the screen turned off. Being very disappointed at first, now I've got used to it and it's OK for me.
The pre-installed RC app is a special build. It seems, unlike its public version from Play Market, it does nothing more than RC.
Well, it may sound as too much quirks, but, considering unique form factor, I'm quite happy to move from Atom, which was, and now Jelly 2 is, my the only phone!
There is a flip cover available from this brand. Protection is better than nothing, but its cheap and on Amazon are some reports it does not fit well, but I had this one before and I think its good enough.
And there is the foto-kontor book style. Also cheap quality.
I am still looking for a solution for cycling. I made one myself from a TPU case with a screw through it from a metal bicycle holder, but maybe there are better and nicer solutions. From a 3d print or something.
There's an old keyboard app that I liked from a long time ago that has full keyboard, t9 style keyboard, and more. One feature I really liked is the ability to swipe between different keyboards if I need to be more precise than the T9 at times. It's simply called Smart Keyboard.
https://play.google.com/store/apps/details?id=net.cdeguet.smartkeyboardpro
I just ordered a Jelly 2 so will be installing this app on it when it arrives on Tuesday :) Hopefully it's still good
I'd try an battery app like AccuBattery to get more details on the charging & battery.
if you really want to make sure the software is not the issue flash it, else it's a Hardware issue & if it's still under warranty you may try to get a new one.
what happens when you plug it into a PC?
I like this app, accu battery. I've only had jelly 2 a few months, bought it new but battery health is 86% capacity. Seems accurate with the poor performance. On my 3 year old tablet it would say 93% capacity much higher than I'd guess after fairly heavy use.
https://play.google.com/store/apps/details?id=com.digibites.accubattery
For stock Android 11 it seems to be ZaZa Remote (com.tiqiaa.icontrol was for Android 10), but I would look for something else. It has a lot of background activity connects to half the internet and requires many permissions. For some reason it disapeard from Play Store. I use IR Remote. It's quite outdated, but works just fine.
How is gsi rom working for you? I had many problems running it in the past (headphones not working, radio not working, LED blinking irregularly, stuttering while scrolling, some process taking 7% CPU at all times). Did things improve?
The app i can recommend because the adaptive screen light can sometimes be flakey is this https://play.google.com/store/apps/details?id=com.rascarlo.quick.settings.tiles I put a brightness tile first with three different modes
I know it defies the idea of carrying a tiny phone, but know that with any Android device you can connect it with a Bluetooth keyboard or Bluetooth kb+mouse combo like the Rii i4 mini keyboard
I am personally more of a frequent user of Logitech multi-device keyboards (the now OOP K810) for both my Windows tablets and Android phones. I like how easy it is to switch devices with those.