I find it annoying having to block the specific sites I do not want leaving cookies on my devices on each and every one of my device and on every web browser. And some browsers make it difficult not handling wildcard blocking properly.
So, it would be interesting to have the ability to have a cookie domain blacklist on which domains you wish pi-hole to strip cookies from in both directions (in case you have been on 4g and come home)
If pi-hole is running a proxy server that take ownership of the domains you wish to block cookies on, terminate https at that point, strip https, or re-encrypt with self managed certificate chain (maybe remove the HSTS headers too? :S)
And yes, I do understand this can be troublesome if someone for some reason want to do it with youtube, it will push a lot of traffic through pi-hole on a sizeable network, it has to be used with care and for purposes where it’s needed.
In my case I would like to block pretty much every single news site I visit, or basically anywhere I consume public static content.