I absolutely love Kindle for fiction, but it is just not even a candidate for any sort of technical book. I'm actually considering getting an iPad for that purpose.
I haven't actually bought one yet but if been using another laptop with Dane dude 1080p screen and it works well. Plus chromebook is pretty caoable as a secondary device so its relatively good value proposition.
Apparently Samsung's Chromebook Pro replacement will have a stylus though, so that should be out in 2018 if you can wait.
I don't understand why they can't fix this, at least for O'Reilly content. Even if they choose to use HTML/epub for SBO, why not generate the graphical version of the equations using the same technique used for the PDF versions?