The Chinese ereader maker Onyx has a couple new 6" devices due out later this year. The Onyx Boox Poke is a more basic model running Android 4.4, while the Onyx Boox Poke Pro is a upgraded model with a faster CPU and running Android 6.0.
Both devices have a 300 ppi Carta E-ink screen with a capacitive touchscreen and color-changing frontlight, Bluetooth, and Wifi, and according to the product page the Onyx Boox Poke has a 2.5Ah battery (there's no listing for the Poke Pro yet).
The Onyx Boox Poke has a 1.2GHz quad-core CPU with 1GB RAM and 8GB internal storage, while the Poke Pro has a a 1.6GHz quad-core CPU with twice the RAM and internal storage.
It's not clear why Onyx chose to run an older version of Android on the Boox Poke (perhaps they wanted to encourage upgrades) but it will severely limit what you can do with it.
The Poke Pro, on the other hand, is going to be the most capable 6" Android ereader on the market.