Block all Meta domains, stop them profiting from your browsing data! Even if you don’t use Instagram, Facebook or whatever they’ll track you across the web with third-party assets.
I just tried to search for a blocklist. Not easy to find. This one looks promising though. There is also a link to another repo containing subdomains (which should not be needed but could be more recent)
Firefox's default total cookie protection is the real solution for this. Yes there is a facebook cookie on reddit, but it is sandboxed from the facebook cookie on cnn and the facebook cookie on youtube.
Also the noscript extension. It takes a while for you to curate your whitelists, but it is easy to do and nothings get to run without a active considerarion.
That’s essentially what I do. Apps track like crazy too so browser-only solutions aren’t my speed. I don’t use PiHole but I have a script that smashes together a bunch of blocklists and exports them to Unbound.
They’re all over GitHub, you can usually just search the web for “X domains” or “X block DNS” (keep it vague because the language always differs) and you’ll usually end up on someone’s GitHub repository.
One excellent list I consider the base of my strict blocking is HaGeZi Ultimate but of course that blocks much more than just Meta.