Nope, the reason why you get these prices on Xbox is because Microsoft allow you to buy Full Digital games from 3rd parties meaning you don't have to buy from the Xbox store, Sony do Not allow you to buy Full Digital game codes from 3rd parties.
No, it was only published by Activision. From Software still developed it.
I've been doing it for years (and on PlayStation) and I've had no trouble FWIW.
Just realised this game is made by activision
Sorry if I’m asking a silly question but is there any risk of being banned or anything by buying games from other other countries Xbox stores? I’m familiar with using VPNs and didn’t realise until I read your post how simple it is to redeem the code and get cheaper games