How to create a batch image processing algorithm?

Question

Images

Question for Photoshop experts.
There are several hundred PNG images that are in the "A" folder. All pictures have the same size 100x200px. Separate from these, in another folder (B) is another picture, also with dimensions of 100x200px.
The task is to overlay a picture from folder B on each of the pictures in folder A, save the resulting result in PNG. I want to record a sequence of actions and use it in batch processing.
Tell me how to do it with a minimum of clicks? What tools to use?
Describe step by step what I need to do to record a sequence of actions to process a single image.

Answer 1

First, open and copy the contents of picture B to the clipboard.
Then open any of the pictures A. Enable action recording. Press CTRL+V and disable action recording. That's it, don't save this picture, just in the File->Automate->Batch menu, specify which folder to process with your new action.

Answer 2

I don’t know how Photoshop (it seems it can’t), but for the mass application of watermarks there are programs like "Photo Watermark Professional"