I definitely have no luck with e-readers with LEDs on the sides. It's the last one I'll buy. If you're not too fussy about lighting you might enjoy the PocketBook Era.
KOReader works fine. I have installed version 2022.06-06 (the following ones give me problems with dictionaries, just like with Android) to test the WI-FI issue and no problems.
And about the ergonomics, I find it too heavy to hold with one hand, but it's a personal problem of mine because it has also happened to me with the rest of the e-readers I've had from other brands. Apart from the first Oasis (without cover) I have never been satisfied with the ergonomic shape of e-readers.
All in all, I am personally very disappointed with the PocketBook Era. If anyone wants a different opinion I recommend you to visit the German forum
https://www.e-reader-forum.de/t/pock...rungen.158884/