For me one of the best ways until now to get good quality IT books is (believe it or not): Humble Bundle (https://www.humblebundle.com/)
The past year they featured bundles from (quickly out of my head): O'Reilly, MIT Press, Manning, Pearson, Pragmatic Programmers and No Starch Press.
Oh, and Packt. But I left that one out because the quality of most Packt books is total shit (IMO).
It's the next best thing besides going on the seven seas if you want to reliably read IT related books on a ereader without spending a ton of money. (book bundles go for about $20 to $30 each, with most if of not all of them totaling up to $1000 or sometimes even more in value).
If you're fast there's still time to get these right now:
15 Linux/DevOps related books from O'Reilly: https://www.humblebundle.com/books/linux-from-beginner-to-pr...
20 Data Science/Data Engineering related books from O'Reilly: https://www.humblebundle.com/books/data-engineering-science-...
18 Hacking/Cybersec related books from No Starch: https://www.humblebundle.com/books/hacking-no-starch-books
19 Software Architecture related books from Pearson: https://www.humblebundle.com/books/software-architecture-pea...
29 AI related books from Manning: https://www.humblebundle.com/books/ultimate-ai-algorithms-an...
21 Microsoft Certification prep books from Pearson: https://www.humblebundle.com/books/microsoft-certification-p...
19 books on Software Strategy and Risk Management from Pragmatic Programmers: https://www.humblebundle.com/books/software-strategy-and-ris...
I used to buy almost every single one of their bundle, but at some point I got a feeling they started repeating with different bundle titles.
Fanatical also has tech book bundles.
Back when I subscribed to O'Reilly I had a bookmark set up to search there with Packt excluded. Otherwise no matter what I searched for the results were clogged up with Packt-slop.
I was once asked to review a Packt book on a subject I knew well. Not only did it contain many factual errors, I wasn't allowed to point them out for correction - they rejected those suggestions. As I recall they wanted my free labor just to review presentation and basically rubber stamp it.
Have never bought from Packt since.