Does this contribute to macOS's suitability for DAW applications or is that more the baked in low-latency audio drivers?
CoreAudio probably deserves most of the credit, there. Similar ASIO-style solutions like JACK, DirectSound and now Pipewire hit the sub-30ms mark without any big scheduler tweaks.
Audio actually runs on a dedicated realtime thread. This used to be scheduled differently, but nowadays it might be implemented by the FIXPRI bucket described in this document.