Question What is a good approach to creating abstract animated backgrounds?

I am getting inspirations for my 2D game from background implementation of games such as Data Wing. However, I’m quite new to graphics like shaders etc.

For starters, if I just want to get a gradient background that animate its colors by lerping over time, is it possible to do so with the UnityEngine.Gradient class somehow attached to a sprite renderer with a white pixel as the sprite or is it better to do so with shaders perhaps for performance reason as perhaps shown in this Answer ( https://answers.unity.com/questions/1637389/how-can-i-make-an-animated-color-gradient.html )?

If I want to create some shapes scaling up and down in the background as in some stages in Data Wing, is it better to create a bunch of GameObjects with sprite renderer and scale them in a background GameObject in an animation that I would record via keyframing, or are there other ways to achieve this effect that may be less tedious or may result in better performance?

Sorry if my question is all over the place. Any guidance would be much appreciated!