To me, it's all about the reading.
I will take a reverse-engineered format if that is what it takes to read.
But I hope you are as strongly against e.g. DOCX as you are against AZW3.
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There are a few generic E-Ink tablets which run Android and have the Google Play Store. They have that wonderful eye-friendly E-Ink display in combination with the freedom that some people prefer, to run any ereader app.
Of course, it also costs money whereas you have a free device already.
