I just got this via email and I'm very disappointed too. DRM issues aside, Kindle is still terrible for tech books. Code samples, data tables, etc. They all look crummy. The pdf ebooks from the Oreilly store had far superior formatting.
I have stopped buying Kindle books due to no longer being able to back up the files (KFX switched to a new encryption type). I rarely buy technical books, but O'Reilly was my go-to due to actually being able to have the real files offline.
Edit: Okay, Google don't make it easy and there's no way to do it from Android. Go to https://books.google.com.au/books and click on a book in your library. If the publisher has allowed it, there'll be a cog in the upper right corner that will have "Download PDF" and "Download EPUB" available.
You have to use their general search product to find enough info to bring up the exact title you want to buy.
For example you can't on the play store find all the oreilly books that aren't drm encumbered or find all the books on a certain topic in a certain range of years directly via its interface.
I wonder why.
In fact I remember that when Youtube got adquired by Google search got worse.