I’ve been doing a fair amount of cleanup the last month or two, taking care to actually unsubscribe from stuff that I don’t want (but in some sense signed up for). In that process I’ve unsubscribed from probably 30-40 sites recently. All but one of them had an “unsubscribe” link that worked without login - the exception was one that required a login I no longer had, and actually generated an angry mail to their support. Of the rest, about two thirds required a button push and then gave the “unsubscribed; sorry to see you go” page. The last third just unsubscribed me directly and without further prompts. None required typing in an email address (apart from the one exception I mentioned).
I mention this as a data point for best practices. Do have an unsubscribe link. Don’t require login. Don’t require typing in an email. Don’t worry about forwarded digests.