I've been adding Argentina region locked games to my Australian Xbox account for a while, you need to be using a VPN with an Argentinian server, no other cache or login requirements and I can confirm that my Xbox account is 100% Australian region.
You go to redeem.microsoft.com on a browser while the VPN is active and attempt to add the code, it should take several attempts but once it gets added, the game is available to download on my Australian non-VPN Xbox. For the VPN I used Keepsolid VPN Unlimited, Which was previously free via OzBargain, not sure about right now.
The ALLK3YSHOP code only helps with some of the payment fee, before the fee you should be paying €2.27 if you scroll down the page and select a cheaper listing of the same product.
The single code came with all 3 games + DLC;
Metro Exodus Gold Edition (Xbox One/Series S/X)
Metro Exodus: The Two Colonies
Metro Exodus: Sam's Story
Metro 2033 Redux (Xbox One)
Metro Last Light Redux (XBOX One)
Here are some more Argentinian region games;
Dead Cells + all DLC is €4.21.
Murdered: Soul Suspect is €1.99.
The Witcher 3: Wild Hunt GOTY is €1.59, (Series S/X version will be free).
Homefront: The Revolution is €0.77.
Assassin's Creed Triple Pack: Black Flag, Unity, Syndicate is €3.39.
Sekiro: Shadows Die Twice - GOTY Edition is €8.94.
Elden Ring is €27.64 (A$42)
Shadow Warrior 3 is €6.95.
Evil Dead: The Game is €6.29.
Evil Dead: The Game - Deluxe Edition is €7.99.
I've been looking for a better code that is high enough to match the payment fee, sometimes I find one that is up to -8%, if you find one please let me know so I can replace the -3% discount code with it.
It needs to be said again because many people miss it, but Enebas price at the top of the page is not always the best price. Scroll down the page and see if another seller is offering it cheaper, sometimes the difference is huge. Eneba is not the seller, they are the selling platform.
The Xbox AU account via Argentina VPN has worked for me everytime over the last year, it just takes patience to keep attempting to input the code with a slow VPN.