The Kindle Fire 8 GB 7-inch tablet, at $50, is a great device to keep Amazon books and music offline for access anywhere.
If you have very many books or a lot of music, you may need to get the 16GB model or add an SD memory card.
Of course, such a device is a little small to use as a book sized tablet and a little bit large to use as a phone---which indeed is possible where you have Wi-Fi.
Still it works and is worth the low price even if used mainly just for storage and offline use.
To be really useful, though, it needs Google Apps capabilities. It comes without them but so far Amazon has not stopped anyone from adding them.
These can actually be added using a PC or Mac. Both the device and PC need to be set up for the process and a batch file needs to be downloaded and used.
Then the 16GB internal memory model applies if you need to store Google Books.
If that is too much trouble, Barnes and Noble offers a similar device which has Google apps right out of the box.
They also have a more expensive Samsung tablet with Google apps.
The Kindle Fire does have the Alexa app which is handy if you already have an Echo.