I tried koreader on a kobo. I wouldn't call it trivially easy when I installed it last year, and I promptly uninstalled it and removed all the hacks so I could get back to a sane installation of the Kobo OS again.
I think maybe for a kindle it might be worth it, but the reality is for Kobo, it's probably more hassle than it's worth.
I found my time better spent setting up a calibre-web in a docker container and then having my kobo sync to that. And that was awesome.
I don't remember frankly, maybe something with the script, maybe something with KFMon. Lack of integration with the Kobo OS itself? Maybe it had to be rooted to install KFMon, but I was reading Koreader could just run inside nickel menu maybe? But yet the script installed KFMon?
Again, I don't remember. And whatever it was it's not worth me trying to reinstall it just to remember what it was, and then to uninstall it again.
The installation instructions are a bit windy, so many people miss that there's a simple script that automates the install for you.
The one thing you have to watch out for : You need to return those scripts whenever Kobo has an update. You won't lose your data or anything but a standard Kobo update dialed disables Koreader
I think maybe for a kindle it might be worth it, but the reality is for Kobo, it's probably more hassle than it's worth.
I found my time better spent setting up a calibre-web in a docker container and then having my kobo sync to that. And that was awesome.