I can't imagine you could do much. I know some ad blockers are optimistically resolving these CNAMES to see if they resolve to a tracker then block them. It'd b

I can't imagine you could do much. I know some ad blockers are optimistically resolving these CNAMES to see if they resolve to a tracker then block them. It'd be hard for a browser to generically identify who the first party is because it could anyone you want it to be.