I was able to "side-load" the azw3 to the Kindle app by copying it to the phone's internal storage -> kindle folder. One problem I've found is that when I try to copy text, I get the "exceeds the copy limit" error (
screenshot). Also, the text-wrapping in the azw3 as seen on the Kindle Android app
looks like this, which still doesn't look as good as
it does on epub with the Google Play Books Android app.