I listened. What I heard was typical Congressional posturing, grumbling by the faltering GOP about discrimination toward them (duh, what do they expect), uninformed questions, and darn little about antitrust.

And can someone tell me the products where any of them have a dominant market position?

As to taxes, as Tim Cook said (paraphrased ) “We follow the law. If you don’t like what we do, change the law.”

This was all political theatre.