Pihole has always worked as expected on my Pixel phones. To the point that I have to drop off of our wifi to visit some sites when they don’t load correctly. Pihole is happening at the router level though, not a setting on my phone. Unless Android starts tunneling around it (I wouldn’t put this past Google), then all traffic will continue to go through Pihole since it’s going through our router. Any device connected to our network has Pihole as its DNS.
Makes sense. We send everything through it by default and then we have a separate device group for non-Pihole DNS handling. Devices such as work computers that might get weird or have issues get put in this group. Everything else is by default put through Pihole until we have a reason otherwise.