The details are different, but what they want is the same: What is the next step in developing my idea?
The next step is to prototype. Then iterate on that prototype (meaning make another, better one with what you learned) to develop your idea beyond the drawing board.
The most useful kind of prototype for development is the Functional Prototype. The functional prototype demonstrates how the idea is supposed to work. It doesn't matter what it looks like, or how big or ugly it is. It only matters that it is the thing that shows "my idea works like this."
Start into prototyping as soon as you can. Anything that iterates and grows the idea. Even just a proof-of-concept, which is a much more limited form of prototype that simply focuses on one piece of the idea and shows that it can work.
I have been designing and building things for a living for over ten years now, and one observation I have that holds true across any kind of design & development - whether professional or hobby, software or hardware - is that the real learning and development happens in iterative prototypes. Every idea comes to life in your head or on paper and gets fleshed out there.
But if your idea is staying on paper and you're not breaking it (or your prototypes) by finding flaws when trying to turn them into prototypes or proofs-of-concept, then you're not actually developing the idea. And you're probably not learning anything either.
Move to prototyping as soon as you can, fail as early and often as possible, and fail as cheaply as possible both in terms of time and materials.
That is the next step in developing that idea you have.
If you're serious about developing a new idea, hiring a consultant like me (at AE Innovations) can save you time and money by helping you to focus on what matters instead of having to waste time and money figuring it all out by yourself.