The existence of physics beyond the standard model has been concretely established based on the observation of neutrino flavor oscillations and it has open many questions about the neutrino's intrinsic properties, including the absolute mass, Majorana or Dirac nature and the relative mass hierarchy of the neutrino. Germanium (Ge) ionization detectors with their unique features and diverse applications in fundamental research are novel candidates for such a search. The TEXONO Collaboration has been pursuing the research program on low energy neutrino interactions and light WIMP Dark Matter with Ge-ionization detectors at the Kuo-Sheng Neutrino Laboratory (KSNL) in Taiwan and in the China Jinping Underground Laboratory (CJPL) in China. We present highlights the potentials of Ge-detectors for the studies of active neutrino electromagnetic interactions, light WIMP, sterile magnetic moment and neutrino-nucleus coherent scattering.