The only sources I can find claiming him directly to be a Satanist are Christian ones.

There's plenty of evidence marking Naples out as a place where occultism, spirituality and esotericism flourished during that time but as far as I can tell the only mention of the Devil or Satanism is when Christians decided a place or statue or person was Satanic. It feel revisionist really.

PS - be careful about online converters, they're not all safe in terms of privacy and some store copies of what you've uploaded. I'd recommend Calibre (calibre-ebook.com) which runs on your PC/Mac/laptop. Also worth noting that conversion is likely against most sellers T&C's.

You're either buying from the DRM-free section or you live in an area where DRM isn't enforced.

*Some* of the books Kobo sell are DRM-free, its true but the majority can only be read via their devices or apps. If you can't transfer your book out of their ecosystem to store how you want and read on any device you own then you don't really own it.

That's one of the things that DRM allows sellers to do. The best solution is either a paper copy or an ebook that's bought from a bookseller that allows you to download the file - then back that file up to a harddrive or remote server. Not many sellers allow that though. This is why DRM sucks.