Here are some details based on my personal experience (I have been under 6 different visa status over the last 15 years).

There is a misconception that an investor visa requires cash investment (in the order of $500K to $1M). That's false. This number comes from the EB-5 green card route. The E visa is a temporary visa, but it is valid 5 years and renewable pretty much as long as you want. There is no minimum cash investment required in the statute.

You do need to convince the US embassy of your home country that you have a good business plan. Actually, to be convincing, it better be more than a plan: early customer interest, letters of intent (LOI), etc. all constitute strong elements to include in your application.

In line with PG's idea, letters from prominent VCs about their interest may work as well.

For about $6,000, you can get a good, proactive immigration lawyer to prepare your case, assuming your business opportunity is real.

Unfortunately, this doesn't work for non-treaty countries. India is one of them

Thanks for the update. As the above comenter says, apparently Iran is a treaty country but India is not. Nothing against Iran, I'm just referring to the recent anti-Iran rhetoric in the US, but it's definitely sad. Wish Indian bureaucrats were more effective at their jobs.