It's available in the US, Canada, and a few European countries such as the Netherlands, Switzerland, and Germany. Interestingly, no UK – if you go to the Apple TV refurbished page you get no Apple TVs, but an error message.
Savings of up to $20
The main reason to go for an Apple TV 4K 2022 refurbished model is that it's coming directly from Apple itself. The savings may not be as impressive as elsewhere, but they've all been reconditioned by Apple's expert repair engineers using Apple parts, so they're going to be as good as new.
The Apple TV 4K is a great addition to any home cinema setup and will give you access to the best tv shows on Apple TV Plus as well as the best movies on the streaming platform.