When I’m using VPN, my pihole can’t see the traffic, and won’t be able to block any ads or analyze the traffic. Also, some browsers use their own DNS, so the pihole can’t block that traffic either.

Other than that, the pihole is a great tool to figure out what’s going on in your network. That’s how I found out that an Android phone is super noisy in my netwrok. Then I installed LineageOS+gapps, and it got better. It was still a bit noisy, so I reinstalled LineageOS, but this time without gapps and no play store. It finally got to the level I like, but unfortunately the world around me wasn’t compatible with this phone any more. :( But anyway thanks to pihole, I was able to figure out what kind of changes I need to make so that I’ll get the level of privacy I’m happy with.