Probably not. I haven't been able to dig into what they're doing, but I watched the presentation about the feature, and it's an opt-in API for applications. I'm not clear on this but I have to assume that the macOS/iOS resolver code is still leaning on your external recursor to do the DNSSEC validation stuff (otherwise, it's going to generate _a lot_ of extra lookup traffic), which means it's going to trust whatever your PiHole tells it anyways.