If your in some strange edge case where your subscribing to services and then discarding your IOS devices before canceling , that's on you. In a worst case scenario you could borrow a friend's Windows PC. As much as I love Linux I can't imagine most Linux users don't have at least one windows PC or Mac.
If we really want to get technical, spin up an AWS instance, RDP into it, install iCloud for windows and then cancel your subscription.