Hi there. I'm not new to e-books but I just discovered this forum. I've been using my Android phone (I know

) for Kindle Unlimited with the Kindle app, and using the built-in e-book app for other sideloaded books.
I'm now considering an e-book reader as I've realised I don't really read much on my phone due to the small size and overall user experience. What would you recommend as a first e-book reader? I might sometimes need PDF reading capability, and I also plan to use Calibre. Also, would something other than the Kindle be able to access my Kindle Unlimited library/books, whether by sideloading or conversion etc?