Ask HN: What's the state of the art of BCI in 2023?

I am interested in continuing my study on something related to BCI in the near future because I thought VR using only audio visual is lame. But does anyone know how's the state of the art today? The only thing remotely on the news is Musk's neural chips experiment. Also is there any recommendations on what books and courses can guide me as a mere software engineer to start with this field?