Amazon.com is releasing the Fenix 5 plus TODAY (Tuesday 19th June).
This link should take you through to one listing where all the variants can be chosen. To get the 5X plus you have to first select the large case size.
Amazon.co.uk release is 28th June. Potentially the 5X plus may not be initially available on Amazon in Europe and another organisation may have the initial sale stock.
amazon.de and amazon.fr have listings but I am not entirely sure that they are complete.
For what it’s worth I’ve bought one through Amazon…I have no relationship with Garmin. No freebies, no PR samples. Nada. Zip. Rien. Nothing. I’m just exactly like you..a Garmin customer.