Abstract: Regional target speaker extraction (RSE) aims to extract speech originating from a specified angular region, relaxing the requirement for precise target speaker location when performing location based speech extraction. However, existing RSE methods typically assume a fixed microphone array configuration and microphone number, limiting their applicability to unseen microphone geometries and varying numbers of microphones. In this work, we propose a geometry-aware RSE framework capable of extract with varying microphone array geometry and microphone numbers. Specifically, we introduce an attention-based multichannel front-end to encode inter-microphone phase information, together with a spatial audio reconstruction-based auxiliary objective to improve the front-end spatial representations quality. Experimental results demonstrate that the proposed framework improves SI-SDRi by 5.1 dB over geometry-aware baselines across microphone arrays with four-microphones, while maintaining a performance gap of less than 0.6 dB compared with a tetrahedral geometry-specific baseline when evaluated on the tetrahedral microphone array.