In the past companies have been known to take more orders than they can fulfill. Some may only have a rough idea of how many Sony will give them. As many of the websites are struggling to cope, they may even end up selling more than they expect. There is talk that Very have already started to cancel some preorders. I haven't paid Game a penny yet, they could cancel my order tomorrow and not even worry about refunds etc.
I noticed earlier that the Ebuyer store page says "All pre-orders are reported daily to Sony for stock allocation, a pre-order does not guarantee stock on the launch date."
Amazon is the gold standard preorder imo, especially if you get in at the first wave of their orders. They will already have mountains of them stashed away, they own their own delivery network and have excellent Customer Service.
Just a few days ago shopto cancelled every preorder of the new Mario game because they couldn't get enough stock:
https://www.eurogamer.net/articles/...rs-blames-nintendos-woefully-short-allocation