alt Hacker Newsremarkable / remarkable2 also work with KOReader. KOReader provides a very good ereader experience - can import dictionaries, export word lists (ie it tracks words you look up), and supports numerous ebook formats and lets you modify the padding/margins/layout. A very good piece of open source software
It is very good except the UI could really use some love IMO. I use it on all my kindles but it really took some doing to get there in terms of getting comfortable with using it.