Projecting Sky onto a background plane

 Sky on a background - Great results with the need for HDRI.

Camera rotation matched and paired with plane

1. Create a plane - rotate it to fill the background.

2. Select the camera.

3. Ctrl+C and hit Copy Rotation. (This requires the add-on Copy Attributes to be enabled.)

4. Make the camera the parent of the plane. Ctrl+P, keep transform. Now any time you move the camera, the plain moves with it.

5. Get a sky image. Connect it to both the Base Color and Emission.

6. Align the sky image horizon with the scene horizon.

7. Tab A, U, C to correct UV.

8. You might need to flip the photo to get the light source consistant. Scale -1 on the x axis.

9. You may need to uncheck shadow on the plane's properties, if the some is casting from behind it.

The end result