Interesting project. I tested on several devices and browsers and: "typography", "grid" and "goodies" look good, but "forms", "tables" and "buttons" aren't quite polished IMO.
I would also buy if there were a PDF version. Since my entire library is pdf, I won't install a software and register an account just to read this book.
Whatever stack or solution you want. IMHO what matters is the monthly bill: everytime I tried to use something from Amazon, I ended up paying too much. Of course, this is all relative and very subjective :).
Yes, you are right: if you need all those things you mention, than hetzner is not an alternative.
However most startups an small busnisses don't, and maybe never will. I mentioned Hetzner because it's the most known here, but there are many other similar providers.
I'm using several Strato root servers since almost 10 years and never had an incident so far, even if it's "low" availability.
Compared to Hetzner. Not a cloud provider, but a root server provider. It's also more expensive than Strato - also a root server provider. Of course, not with the same availability, but for most startups it's more than enough.
Considering that there more iOS apps than Android out there (at least according to the AppStore), I would have exected exactly the opposite direction translator from google.