Launch speed

Which speed is required for a launch vehicle to achieve LEO when starting from the earth's surface?

9.4 km/s and additional 1.5-1.6 km/s are used on aerodynamic and gravitational losses, however, the https://www.skyrora.com/third-stage which can launch a payload into orbit at an altitude of 500 km to 1000 km has 1,5 km/s speed.