Create Environment map in Blender
For more realistic map we should render in cycles.
In Render Properties set Max Samples to 256 for Viewport and Render
In World Properties you can set the Surface color to black if needed.
In Output Properties under Format set the Resolution to a power of two like 2048x1024
Add a camera, set x rotation to 90° and under Object Data Properties set Type to Panoramic and the Panorama Type to Equirectangular
Check that in the Object Properties the Camera is checked under the Visibility section.
Then render with F12
Then save the render with alt+s and set Radiance HDR as the file format.