Valid question, aware of it as a response to this question, but it doesn't address the orginal question. If there's a existing notable service doing customer developement as a service, the fact they exist might provide an answer to your question.

Maybe one way to rephrase the question that might be more common might be:

Is it okay as a co-founder to let another cofounder handle customer development if they're more experienced at doing it? Or as a non-technical founder, is it okay to outsource development?

My experience is this is super common, and as such, if a solo founder is not experienced doing customer development, it would make sense at the very least get help doing customer development.