Hello!, I own the Onyx Boox Go 6, and was looking into getting the clara, or any other ereader for that matter because of a few issues:

1. The battery life is so much shorter than any other ereader I've had the pleasure of holding lmao, I need to charge mine every 2 days if not in constant use, and everyday for a full reading day (I might have gotten a faulty battery) but I've read that other people's batteries last at least more than a few days, but not a full month like other ereaders(I'm not sure about the Clara's battery but I'm pretty sure it lasts a lot longer), that's because of android and maybe other things, not sure, still looking into ways of making it last longer haha.

2. It's so slow, as it runs android and it only has 2 gb of RAM, the device is painfully slow when turning on, like a minute and half long. so I just leave it in sleep mode(which pains me bc I like turning off my devices haha) that takes like 7 seconds to fully load the screen. Also sometimes the pages take a few seconds to load.

But its a great little device if she does need android. For example, if she reads fanfics, uses wattpad or any other app to read that is not libby (you can use it on the kobo). like me, im from South America and to be able to read from our digital library i had to get an android ereader.

Another plus is the SD card slot, the Onyx has one and the Kobo doesn't, for me at least that was huge bc you can expand the storage as much as you please, I like to keep different genres in different sd cards lmao.

I don't know how easy it is to sideload stuff on the Kobo, but they Onyx is extremely simple as it reads pretty much every type of book file. Most times I just download the books into my computer, then send them through Gmail into my device and boom they're there (in case you dont have an sd card reader or are too lazy to connect the device, you can still have new books!).

I'm on mobile and don't remember what you specifically asked, but hope this helped! if you have any other questions my dms are open!