Substitutes for IBD/ PE experience to get into development finance

My goal is to get into development finance (e.g., World Bank/ IFC, ADB, AIIB) or impact investing. I have observed that most development finance institutions or impact investing funds typically recruit from investment banking or private equity. If investment banking or private equity is not realistic, then what other finance roles would be the best substitute for IBD/ PE?

My initial hypothesis for reasons why institutions like the World Bank would prioritize IB or PE candidates was because those candidates bring with them “proven” skills in modeling. According to that logic, one would believe that a research analyst role at a long-only hedge fund or credit rating agency would also help develop comparable skillsets, but I just don’t see how plausible that is. I worry that this may be a naive, overly simplistic view of the world. Perhaps IB/ PE candidates are sought after (aside from prestige) because their ability to handle the somewhat administrative(?) tasks that come with structuring and closing a deal is no less important than their intrinsic modeling skills? Or is there something complicated about development finance buyouts that make the financial models in public equities or credit analysis less transferable? What am I missing?

So back to my original question: what other finance roles other than IB/PE would best position one for a development finance/ impact investing job, and why? Some roles I had in mind to start with:
- Research Analyst at a long hedge fund
- Credit analyst at a rating agency
- Valuation analyst at a Big 4
- Others? (FoF? VC?)