Based on other answers here, it seems Home Depot has a standardized process for considering new products, but there are always ways to increase your chances. Do you know leaders from other companies that have their products there? Do they work with a buyer closely who they can introduce you to? Would their endorsement help your application chances? If you are not already connected with someone whose products are sold there, can you build a relationship with someone?
Although I am sure their decisions are made mostly by the numbers, it never hurts to have the endorsement of someone they trust, or to be the partner who established a relationship today and is remembered when a need arises tomorrow.
As for other partners like builders and developers, your strategy to that would depend a lot on your market. Are you nationwide, with many thousands of companies to target? You might need a solid advertising or content marketing strategy. You may need a lead generation strategy with a solid and optimized follow up process.
Are you local with only 30 companies to target? You need a more refined strategy for approaching them and building relationships, probably in person.
Interviewing your existing customers is a good way to find out how they think, where they go to locate information when they're buying a service like yours, what made them want to work with you, whether they know anybody else who might benefit from your service, etc.
Happy to talk partnership strategy anytime.