Mmm, are you looking for a navigation bar at the bottom or do you want to use the physical buttons?
I haven't been paying much attention to the Glow '21. I'm still using Magisk on it (while my Poke3 has gone Magisk-less).
I remapped the physical buttons on the Glow '21 in /system/usr/keylayout/Vendor_0001_Product_0001.kl
You need Magisk or something else to modify /system
Code:
#
# Key layout file for physical buttons
#
key 116 POWER
key 102 HOME
key 191 APP_SWITCH # top left
key 192 PAGE_UP # top right
key 193 BACK # bottom left
key 194 PAGE_DOWN # bottom right
The default B&N keys are F9-F12