I have 35+ startups in my background in multiple industries and multiple roles.

There is good advice from others on finding a real problem you inherently know and build a service you and others would find valuable to use. If you do not have this idea (not one suggested by us), it could be the fish and a bicycle cliche, a solution seeking a problem to solve.

What you have not made clear is why you all want to start a business *together*. If it is only that you are three females in a tech-bro world where you all have frustrations where you all (individually or collectively) work, that is not a strong platform for success. Is it that you deeply like each other? Is it that you deeply trust each other? Do you share a common bond or interest in a specific subject (not what you do professionally, but something human)? Do you have other bonds than skills (hint, you all have the insufficient/wrong skills - as all of us did, so you will need more) and gender?

In the 3 Ts - Team, Technology, and Traction, the reason you all want to work together is crucial since it is why you will not fall apart.