It is good to start a hardware-based open source company? How good it will be effective for funding? how does a good business plan look like?
No different than any other business plan. Determine the justification for your premise, validate the marketing strategy (test, refine, adapt). Assume that you will never get funding and let that guide you on what you would do if you never got an outside dime. If you could run your business without outside funds, then you probably have a business. Then it's your job to determine how your business could scale, what the threshold is when you'll need new resources to expand. And you can build your plan.
Investors invest in plans, especially proven plans. What would you do differently in your development if you knew you weren't going to get financial support until you had already won customers and they'd be using your product for a year. What would you do with money to make your 2.0 version exponentially better? How can you get close without money. Those are the kinds of things investors will be curious about.