@aral I don't suppose you'd know if adding these header policies to HTML meta tags would work? I have a few websites that use GitHub and GitLab (.com) Pages, and I don't think I can alter the headers coming from the server.
I've at least updated all my other websites with this! Thanks again for the heads-up!
@Alamantus AFAIK, no. (For one thing, Google isn’t trying to make it easier for you, they’re just trying to cover their asses with regulators – “oh, it’s opt out so people have a CHOICE… so it’s ok”