Fun fact with these Fanatical giveaways, you don't actually even need to sign up (and immediately cancel) their newsletter, you get the Steam key and then they send you an email saying 'please click here to complete your sign-up' or something, which you can safely ignore!
It's not just 'sign up for a newsletter' - I just tried, and it's also 'register an account and link your steam account'. Maybe this is just how it works for Canadians though, but either way it's a big enough turn off for me to not bother.
Oh yeah I did that a while ago so I forgot, but yeah I think that's the case for everyone. Ultimately I think Steam explicitly tells you what info they get and it isn't that much, but that's the "price" for a free game.
No worries if it's not for you though, if your Lemmy client lets you block posts you can set up a filter for Fanatical and you shouldn't see any more giveaways like this.