I haven't used my Kindle without an account, but I have put non-Kindle, non-Amazon books on it, including some PDFs.
In my experience, the Kindle is terrible for reading PDFs. The screen is small, and PDFs don't dynamically resize the way e-books do. You'd probably be better off with an iPad or other tablet with better PDF software and better ability to zoom and pan than the Kindle has.
Thanks. I don't expect a great experience but I'd like to see if a eInk reader would be easier on my eyes since I am already 10 hours a day on LCD.
The following video gave me the impression that pdf on Kindle Oasis was acceptable...
In my experience, the Kindle is terrible for reading PDFs. The screen is small, and PDFs don't dynamically resize the way e-books do. You'd probably be better off with an iPad or other tablet with better PDF software and better ability to zoom and pan than the Kindle has.