We theoretically introduce a quasi-one-dimensional magnetic heterostructure of alternating 2D topological and normal insulator strips. Such a structure can be realized by special fabrication techniques or may emerge naturally in twisted bilayers of certain transition metal dichalcogenides. Its low-energy physics is governed by a hybrid Hamiltonian intertwining the Su-Schrieffer-Heeger and Shockley models, with spin-momentum locking and local Zeeman splitting. Symmetry analysis places it in class AIII, characterized by chiral symmetry and a $\mathbb{Z}$ topological invariant. Computing the winding number from the block-off-diagonal structure of the Hamiltonian reveals topological phases characterized by invariants $\nu =0$, 1, and 2. Furthermore, a single magnetic defect acts as a sensitive local probe, whose in-gap spectrum provides a spectroscopic fingerprint to distinguish global topological phases. We show that the frequency-dependent optical absorption induced by such a defect exhibits distinct features in the topological and trivial phases, offering an independent, experimentally accessible local indicator of the global topological order. Extending the platform to a multilayer geometry uncovers a nonsymmorphic projective symmetry that gives rise to Möbius band topology.

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• Topological phases of matter
• Topological materials
• Green's function methods
• Symmetries in condensed matter