Your setup page is fantastic! Especially appreciate the status indicating if it is set up correctly on the device I am using. I set it up on Linux, which I notice you don't have a tab for, but that should be pretty straightforward to add. (Even though Linux users may, typically, know how to do this themselves, it might be nice to include Linux as a signal that it is truly cross-platform.)
I noticed inconsistent results on Android depending on whether I had it set up via Intra or as DNS-over-TLS in the native Android settings. Internet browsing was similar to on desktop, either way, but my concern is mostly related to video apps, specifically the ones my family use (Hulu, YouTube, CWSeed). On Intra, all the video apps seemed to work but there were still ads in all of them. For DNS-over-TLS CWSeed stopped working entirely, saying "video playback failed". Hulu and YouTube still worked but they also still had ads, while on Desktop they did not!
These are the sort of issues I was concerned about when considering using PiHole for the whole house. Are these things that can be mitigated on your end, or will they require per-device apps to be installed, and potentially even require rooting the device?
(Incidentally, how is it that YouTube and Hulu get around the ad blocker on Android?)