I really love my boox palma 1st gen. Got it used on facebook marketplace for ~100 dollars a year ago. It's just extremely portable, phone sized. Battery is fantastic. I can easily read anywhere, including on hikes, while laying down and easily navigate one handed. USB-C. Android. Easy to load on koreader (get the bookerly font). Can drag and drop files via usb-c but boox drop also works great and is super easy. I'm very happy with it.

I have a boox air4c as well that I sometimes read on. It's obviously a much more premium device but most of the time I still go right to the palma, just because it is comfier.