i am using ivacy for android box and its working fine plus cheap.
you can see how to configure it here Android VPN - Best VPN For Android
its a step by step guide. Hope it will be help full. feel free to ask anything :)
There are a number of countries that a vpn offer. i am a regular kodi user and I use it via ivacy add on. Its working fine and data my ip is hidden for sure. You can understand how does a vpn work on kodi, search on google ivacy for kodi....
There are multiple VPN to support fire tv. i am using ivacy for online streaming. here is a guide to setup fire to on a vpn How to Setup VPN for Amazon Fire TV/ Amazon Fire Manually