Making orthographic GUI interactive

It’s super simple to set up an orthographic camera and a textured plane to make GUI but how would I go about making it interactive? I do not want to use Unity’s built in GUI. By interactive I just mean having buttons you can press for a pause screen or start menu. I was thinking there might be a way to draw an transparent rectangle and check if the mouse position is inside, but I don’t know how I would make a 2D rectangle on the screen in Unity.

You could give your textured planes colliders, then use raycasting from the ortho camera when the mouse clicks to detect button presses.

or you could have a script on each textured plane that works out its rectangle on screen based on its known dimensions and those of your ortho camera, then do simple bounding box checks on mouse position when the user clicks.

that’s two ways of doing it anyway.