Absolutely. I've been using Kindles for a decade and have never bought any ebooks from Amazon. The only functionality issue I run in to is that as far as I can

Absolutely. I've been using Kindles for a decade and have never bought any ebooks from Amazon. The only functionality issue I run in to is that as far as I can tell, Amazon has a feature where if you buy the book from them then they keep your progress synced between your kindle and their phone apps. Can't use that with books from other sources.