There's no exception for "functional cookies". There's an exception for cookies "strictly necessary" for an "explicitly requested" service. I don't see how remembering you don't want cookies is strictly necessary or explicitly requested. Unless you have a separate optional check for "remember my decision" I would argue that not asking every session would be a violation of the ePrivacy law.
It's good to remember that judges are not computers. They are not required to follow the law to the letter in weird edge cases, especially when that would be against the intent of the law. They are allowed to do that, but not required.
Many common practices are against some particularly pedantic interpretations of the law. Nobody cares, because following the law to the letter would not be in anyone's interests. If an obnoxious asshole decides to really push the issue, and they are not laughed out of court because the judge is an equally obnoxious asshole, the practice may be found technically illegal. There will likely be no consequences, because it was done in good faith with everyone's best interests in mind.
However, the ruling may force the government to change the letter of the law, wasting a lot of time and money that could have been spent for other purposes. All because of some particularly evil asshole.
Do you mean the most restrictive interpretation of the law you can imagine? Because you can't actually know what the letter of the law means in specific cases before a judge rules something.
You can of course try living your life like that, but you'll likely find that it becomes effectively impossible to do anything.
