Here's a reminder that Boox makes amazingly good e-readers in all form factors Amazon does (including a variety of tablets!), with stylus support (USI 2.0 for smaller devices, EMR for their Note series and above), fully open (recent Android versions, regular updates, unlockable bootloader, straightforward to root devices), support KOReader, with a solid built in reader (plus support for cloud sync, including syncing books to a free 10GB Boox server storage), support for OPDS (a better way to access your library than Calibre's sync, plus it can be utilised with most digital libraries too), and altogether quite well priced devices.

At the moment I have on my hands a Go Color 7 gen2, a Note Air5 C, and a Palma2 Pro. The experience is surprisingly good for a "random Chinese brand", the hardware, compared to similarly priced devices, is superior (seriously, 4/6/8GB RAM, 64/128GB internal storage, SD card support), not to mention their customised e-ink waveforms (which give you near LCD-like scrolling with minimal trailing effect and little to no ghosting, something I can't say about my Kindles...)

The only downside I found of these devices is the relatively bad battery life in locked/standby (due to Android, but you still easily get over a week per charge with average use, or about 20-22 hours of active use!), and the speakers... definitely not meant for audiobooks.