Gyromagnetic zero-index media reveal an intrinsic connection between topological photonics and extreme-parameter photonics, offering the possibility of enhanced light-matter interactions. We demonstrate that the boundary branch constrained by the reflection-phase vortex at the Dirac point hybridizes with the gapless modes of a topologically trivial region, forming a spatially extended chiral hybrid response. Experimentally, we designed a heterostructure that utilizes a gyromagnetic zero-index photonic crystal to break time-reversal symmetry. In a single design, a spatially resolved chiral response is achieved within an extension region composed of conventional double-zero-index materials, while the zero-index transmission characteristics of the gyromagnetic region are preserved at the Dirac frequency. Compared with traditional topological waveguides, the proposed structure utilizes almost the entire available space, with its operating frequency remaining stable regardless of the number of unit cells. This work provides an approach for enhancing the efficiency of light-matter interactions in traditional topological photonics.

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• Photonic crystal waveguide
• Photonic crystals