The role of the CTO heavily depends on which stage currently the company is in.
Interesting. In your experience, when should there be a split into CTO / VP R&D roles? It seems in your cases you are doing both.
In our case, what you describe fits our VP R&D. He manages ~40 engineers and team leaders department, and reports to the CEO. The CTO also reports to the CEO, but is reponsible for the longer vision - the innovative projects, strategic partnerships and so on. In addition we have a Chief Architect, who is the one dictating the tech stack and decisions in the day-to-day 😅
I guess every place has a different setup, so it's interesting to see how other startups do it. Thanks for sharing!