IceCube-Gen2, a future upgrade of the IceCube Neutrino Observatory, is designed to enhance our ability to detect neutrinos above 10 TeV via a significant increase in instrumented volume compared to IceCube. We expect an increased astrophysical neutrino detection rate of up to an order of magnitude with IceCube-Gen2, using a combination of more instrumentation, larger string spacing, and enhanced optical sensor performance. A new optical sensor module, the Dual optical sensor in an Ellipsoid Glass for Gen2 (called "D-Egg"), which houses two 8" HQE photomultiplier tubes (PMTs) in a UV-transparent pressure-resistant glass with an optical coupling elastomer, significantly improves photon detection efficiency in all directions. Its elongated mechanical shape is optimized for cost-effective instrumentation of optical modules and high photon transmittance to PMTs. Furthermore, it is optimized to endure high pressures, as the ice refreezing period during detector deployment requires the module to withstand pressures up to 70 MPa. Additionally, D-Egg's readout system takes advantage of advances in embedded computing power, enabling simpler, more efficient event triggering and seamless event recording compared to IceCube. Herein, we report on the design and properties of D-Egg's components. A series of laboratory measurements and detailed comparisons with the simulated design indicate that D-Egg provides a technological solution for IceCube-Gen2.