It's not entirely clear what your situation is, but there are a few possibilities.

If you have only a prototype, but the ability (including capital) to manufacture it and you are seeking to be on their shelves, then you'd be dealing with the appropriate category buyer. But your odds are quite low. Why is your product better than others on the shelf? What kind of price point and sales velocity can be expected? Do you have the capital and capacity to fill an opening order and orders after that (the faster you grow, the more financing you need, because your working capital will never be sufficient based on the pay terms of the vendors). Is your prototype full working and ready for production? Or is it just an idea, because buyers want products to put on the shelves, not ideas that might or might not ever be able to be manufactured.

If you are looking to have someone else manufacture your product, then you probably don't want to go to a retailer at all. They sell products. They're not in the manufacturing business. You'd need instead to deal with manufacturers in your product space, but with one whom you don't compete with or where your idea would advance the state of the art. Then there are question as to whether you have an IP protection or whether you product is fundamentally different than others in the same space. Hence, you perhaps need to be talking either to pharma companies like Merck or to medical device companies like Medtronic (depending, of course, on what your product does).

There may be other possibilities. But there's not enough information in your question to be more specific.

Should you have any specific questions, message me to request a call and we can get into this in more detail.

Steve

Traction, product, and/or connections if you have them.

It's incredibly difficult to enter into such massive retailers as the competition is incredibly high. As a product in the pharmaceutical vertical, I'd also ask about your regulation and certification - likely things that those retailers take extremely seriously, especially in these aisles.

Many companies and small businesses that manufacture products which are then sold in CVS, Walgreens, Walmart, etc... usually start first by carrying their product in independent stores. They build their way up, one small branch at a time, one small store type at a time (independents => chain stores => mass retailers).

The selling gets progressively easier over time, as you have more proof that this product actually DOES sell and is something customers want.

It would be extremely difficult it would be to convince any of these retailers to carry your product when your product isn't a) finished b) has no proof of performance.

Several things that you mention are cause for concern:
- Selling a prototype to these massive retailers implies that you're just getting started. Even if you do get into those stores, how exactly would you prove your ability to scale to their inventory demands?
- If you're just getting started, how good are your financials? You should be aware that of the three you mentioned, Walmart is most notorious for late payments (relative to regular business cycles).

The short answer is:
1) Your product needs to demonstrate a clear appeal to consumers, including the fear factor ("If you don't use this...")
2) This will also affect product pricing.
3) You have to show the science behind it, what is proven and what is new.
4) If required, you should already have the necessary approvals (FDA, etc.)
* Above all, you need to demonstrate that you know the market (present and what's coming) and the industry, and that you know what you're doing.
This is, I can only imagine, a big money deal. Do not skimp on preparation or research.
There are options as well. A "simple" deal where these stores act as wholesalers or some sort of partnership / profit share.
Let's talk about what you are offering!
https://clarity.fm/duanemarch