Websites are free to standardize on a browser extension that provides a conforming interface and use that for users that have it installed, I don't see how the

Websites are free to standardize on a browser extension that provides a conforming interface and use that for users that have it installed, I don't see how the law bans that. Similarly you also don't need to put a full-screen modal to ask people to opt-in for things that require opt-in, you can just put the switches somewhere on the page. But of course many websites don't want to make it easy to ignore opt-in options, but would rather annoy you with. (Although nowadays it's not that unusual to see it done e.g. with social media embeds: locally cached preview image and opt-in button to load the embed instead of prompting on page load)