Pre-AI, it's hard to imagine that opening moves had changed much. Following the birth of computer engines, has AI changed opening theory, and if so, how?
I would say not yet. I would think what is called AI (it is not actually AI but that's a different discussion) has made some people question how they approach chess and maybe led to some ideas but I wouldn't say AI has made any significant contributions to theory.
When matches are held between traditional engines and AI engines they are held in conditions that greatly favor the AI engine. Traditional engines are still way ahead. AI is just the cool new thing.