Custom/off-axis projection matrix

Godot Version

4.2.1

Question

I need to set up a custom off-axis projection matrix.
I found that I can use camera.get_camera_projection() to get the current projection, but changes to this matrix do not seem to be picked up by the camera (a second call to get_camera_projection returns the original unmodified matrix). I also can’t find a setter to set a custom matrix for the camera. How would this be approached in Godot?

This seems to not be possible yet:

As a reply mentions, you “can use the Frustum camera mode with a custom frustum offset, which should cover some of the use cases of a custom camera projection matrix” which may or may not help in your particular case.