m_Camera.SetOrthoProjection(m_ViewFar, m_ViewNear, 256.f); might also work.
Yes, it's a start. Then we need:
Add a separate camera controller to be able to configure the orthogonal mode properly
Add an option in GUI
Adjust zooming code with visible bounds to fit/to be similar to the perspective mode
Choose camera position to have proper sounds on all zooms
Check reflections and refractions
Check shadows (w/ and w/o cover the whole map mode)
Test regular and big screenshots and adjust their code if it doesn't work
Think what do we need to do in Atlas (autoswitch to the perspective mode or something else)
Test for z-fighting for all backends (OpenGL, OpenGL ARB, Vulcan)