You mean if Apple adds the ability to add standard web extensions?

https://developer.apple.com/documentation/safariservices/saf...

Have you tried initing or refreshing the filters?

Adguard’s blocking is quite potent I.e. YouTube ads don’t play

I'm not privy of the technical details.I don't think it acts on cookies themselves, it merely removes the nagging banners, and in that case the EU-compliant site is supposed not to set any cookie or other tracker since none were explicitly accepted.

Basically at a high level it's like what DNT should have been i.e "as a default don't track me since I'm not giving consent"