I’m new to E readers too, TJI. I have a Kindle fire and have to figure out how to set it up.
Wherever the Nook came from(Barnes and Noble) can help you too..You’ll have to have WiFi and a password.
As for using both, I think that’s fine. There are games that they can play on the Nook too.
My ten year old granddaughter still reads voraciously. But the Nook is a fun change of pace and good for travel.
Thanks for the positive and helpful comments, Mountain Mary.