The wave distortion material can be modified in the same way, replace the Texture sample with a SceneTexture node.
The Cutoff transtitions of that tutorial are applied to an image, in full screen, in a widget. You can continue using this materials in 2D with that trick, or you can apply a mask directly to the SceneTexture node.
So the Radial Cutoff Material can be transform from this
to this:
And now can be used in a Post Process Volume, the result is the same.
With regard to blinds transitions I think you have all the knowledge in Transition effects using materials (part 2) – Parallelcube. The most difficult part is to create the gradient mask.
I want to make a short tutorial doing a transition blending to levels at the same time, I dont know when, but I think it would be interesting.