Trying to get away from my phone more, and an e reader sounds like a good way to get myself to read more. Kobo is sounding like the most recommended one based on some googling, but I’m also ok with jailbreaking something like an older kindle from eBay. Something that plays nice with Libby would be ideal but not required. 
I got a free Kindle from work a while ago, jail broke it and put KOReader on it, works like a charm. I haven’t set up calibre-web or anything, so I just turn on the SSH server, connect via SFTP via Termius from my phone, and copy books over.