According to my experience and because I once bought and returned it myself, I can say one thing: No.

Either you take Amazon Kindle directly, so that you have Kindle ex works, but you can only use Kindle and no other suppliers. Or you can get an e-book that runs Android, e.g. Onyx Boox, which allows you to use Kindle, Google Books, your own tools (Onyx app) etc. This is possible because you can download apps directly from the Google Play Store.

There's no point, there's telegram to download comics and otherwise there's a lot of free stuff on the internet.

Unfortunately no