It seems possible to achieve this today with Content-Security-Policy and Feature-Policy[1].
However, even without the help of those headers, one could also have some discipline (perhaps also respect for users) and refrain from putting tracking and other undesirable things onto their website.
This doesn't seem to be a technical problem, so a technical solution - especially an opt-in one - probably won't help.
However, even without the help of those headers, one could also have some discipline (perhaps also respect for users) and refrain from putting tracking and other undesirable things onto their website.
This doesn't seem to be a technical problem, so a technical solution - especially an opt-in one - probably won't help.
[1] https://scotthelme.co.uk/a-new-security-header-feature-polic...