You ask consent from both users to store it wherever you'd like.
Let the service do what it does with least permissions. If something doesn't work there should be a settings where you opt-in. Don't block my view, hoping I will click the dark pattern as you want me to, believing I don't get anything if I say no.
That's not informed consent. That's consent under duress.
There will be some cases where you need to explain what's going on to a customer before they should be allowed to do stuff — medical, financial, probably some others too — but I think the whole thing is getting abused so much it can't stand, and the exceptions probably need a specific license already anyway, and that license can just also say "and you not only get to have the popup, you are required to".
Preferably half that.
(Advertisers are allowed longer agreements because they can be expected to hire a lawyer to explain stuff to them).
In particular, the EU believes that by transferring personal data to the US, it could potentially be accessed by law enforcement/three-letter agencies without 'adequate' process.
More here: https://www.osano.com/articles/privacy-shield-invalidated#:~....
In short, the US does not have "a level of protection essentially equivalent to that guaranteed within the EU".