Is it possible to create a scrolling texture as an image effect (shader)?

So i know about writing shaders for image effects from various tutorials. However, i can’t figure out how to render a separate texture “above” the final rendered image. The texture i want to use has a lot of transparency, so that the scene itself could still be seen.
Is there a way to render this texture above the scene? I imagine it should be possible to hook this texture into the final render image in screen space projection, but I can’t get my head around it.
Pointing me into the right direction would be greatly appreciated. Thank you.

(Not tested but done something similar)

Create a shader that has 2 texture inputs, then a material for the shader.

Create a script that uses OnRenderImage and attatch it to the camera.

Look at code example: Unity - Scripting API: MonoBehaviour.OnRenderImage(RenderTexture,RenderTexture)

Your overlay image will need to be in the 2nd texture slot,
Your shader code will basically lerp from the original scene rendered image to the overlay image, it will need to sample texture2’s alpha channel to see if there is anything to display, then if alpha is 1 or > 0.5 use overlay image color.

you dont need a shader for this. try a script like this on your game object:

public Material m;
	public float x,y;
	public void Start(){
		m = gameObject.renderer.material;

	void Update(){
		x += Time.deltaTime * .5f;
		y += Time.deltaTime * .25f;
		m.mainTextureOffset = new Vector2 (x, y);