Strained germanium (𝜀-Ge) and strained silicon (𝜀-Si) buried quantum wells have enabled advanced spin-qubit quantum processors. However, in the absence of suitable lattice-matched substrates, 𝜀-Ge and 𝜀-Si are deposited on defective, metamorphic SiGe buffers, which may impact device performance and scaling. Here an alternative platform is introduced based on the heterojunction between bulk unstrained Ge and a lattice-matched strained silicon-germanium (𝜀-SiGe) barrier, eliminating the need for metamorphic buffers altogether. In a structure with a 52-nm-thick 𝜀-SiGe barrier, a low-disorder two-dimensional hole gas is demonstrated with a high-mobility of 1.33 ×105 cm2/Vs and a low percolation density of 1.4⁢(1) ×1010 cm−2. Quantum transport shows that holes confined in the buried unstrained Ge channel have a strong density-dependent in-plane effective mass and out-of-plane 𝑔-factor, pointing to a significant heavy-hole–light-hole mixing in agreement with theory. Measurements of Zeeman-split levels in quantum point contacts further highlight this character, showing a two-fold larger in-plane 𝑔-factor in Ge than in 𝜀-Ge. The prospects of strong spin–orbit interaction, isotopic purification, and of hosting superconducting pairing correlations make this platform appealing for fast quantum hardware and hybrid quantum systems. ... Read more