[qwertox]

I would rather have a cookie-based approach where the opt-in dialog is clearly laid out via regulation.

At the top of the dialog a "decline"-button and to the right of it an "accept"-button. These buttons toggle all the toggles of the providers listed below those two buttons. You can then manually override each of the listed providers, which may be also grouped by purpose in order to ease selection. No nested dialogs are allowed.

Upon declination, one single cookie must get set, with a specific name, ie 'consent-acknowledge-status', with an expiry date of at least one week, where the consent selection is stored, so that it can be respected in future visits.