First gather proof that you have customers waiting for your product. Thinking something is a good idea and proving it is are two different things.

Then look for local venture capital via your local Startup groups. You will find that they are frequented by all the "usual suspects" and you will meet serial entrepreneurs and business coaches etc.

Build the minimum viable version of your software. Don't add all of the possible features, just add those to the TODO list. Build something that works and be prepared to re-write when it grows bigger.

Going live and gaining real users (free or paid) is how you prove your idea deserves further investment.

You are competing against glitzy show-off projects involving the latest craze (typically AI at the moment), don't let these things distract you.

You may find you actually do need to work alone and build out your idea prototype first though. People hear "good ideas" all day long.