chatGPT is simply a GPT model fine-tuned in an instruction oriented way to align with human-rated helpfulness, truthfulness, and harmlessness as a reward signal. The diagram on the chatGPT blogpost is literally the same diagram in the March 2022 paper: https://arxiv.org/pdf/2203.02155.pdf

So it seems like Google could easily replicate this technology, but its difficult to deploy in the real world without brand damage.