Game in the UK are allowing people to register online via email to receive a code for the Shiny Eternatus Distribution on Pokémon Sword / Shield, no need to visit an actual Game store to receive one.
Based on past experiences this should also mean people outside the UK are able to receive a code, hopefully opening up the availability of this rare shiny legendary to Pokemon trainers around the world.
Based on past Game distributions this shouldn't be locked to just people in the UK, however if you have a generic email such as an @gmail.com or @outlook.com it wouldn't hurt to use these.
Shiny Eternatus will arrive in your game at Lv. 100 with a Timid Nature and the Pressure Ability. It’ll know the moves Dynamax Cannon, Eternabeam, Sludge Bomb, and Flamethrower.
To obtain a code for the Shiny Eternatus Distribution simply register you email address here on the Game UK website. Game will email codes on Fridays and Mondays, while supplies last.