All the eBooks of my work that I self-publish are DRM-free, including the ones from Amazon, but Amazon have only recently added an option to allow their customers to download these books as ePubs or PDFs, as well as the special format used by Klndle readers.

It’s up to the individual publisher of any eBook on Amazon to decide:

(a) if they want the book sold with or without DRM
(b) if DRM-free, whether or not to allow downloads as ePubs / PDFs, which can be more easily read on non-Kindle devices.

I’ve opted for DRM-free, any format.

Amazon don’t make these choices easy for their customers to discover. DRM-free books for the Kindle used to have the description “Simultaneous Device Usage: Unlimited”, which was already rather cryptic, but now even that seems to have vanished.

Links to all my self-published eBooks. [If you don’t like Amazon, regardless of DRM status and file format, these are all available from many other vendors.]

https://www.gregegan.net/BIBLIOGRAPHY/Ebooks.html