I'm a professional Firmware engineer with 20+ years or product development.
I work for a company that does contract hardware and software development from firmware to the cloud.
All I can tell you is you better research the heck out of this idea, a real product costs 100's of thousands of dollars to develop and more to make and more to market.
Learn what youre doing before you go off and hire someone who will just spend all your money and waste your time
Interestingly so are quite a lot of the people who contribute to this forum
Some of us even use this forum to find work. I actually take the ideas of people and turn them into products without the need to spend the about of money you are suggesting. Most of the projects, by nature of the forum they are posted on, tend to be small ideas that need formalizing into something that can prove a concept.
Mandy should not be put off trying to get her idea to market or even just to proof of concept with half million dollar development quotes.
How do you think Arduino came into being in the first place ?