Technical enough to understand, but probably not technical enough to build (but maybe was at some point). That's where they need to live. Their job is to align the devs and the roadmap with the business needs, prioritize what bugs to fix, and decide which enhancements are worthwhile. They also need to know when the team is bullshitting them and when a tech design is too complex or simple.

I can imagine a non-technical person could end up in this role and succeed, but someone with a technical background and some business acumen will have a much higher probability of success.