It was founded in NYC

https://en.wikipedia.org/wiki/Datadog#History

It looks like it was founded in New York, but in general the process is just making a new American corporation and transferring the French corporation (or its assets) to the American one, and dissolving the French one. Also, getting work visas for your employees and hoping that the bureaucracies don't affect you/deny you/remove your work visas after being accepted.

1. Be a smart cookie

2. Move to US on a visa (typically H-1b)

3. Get green card (hope politics don't kick you out with immigration bullshit bureaucracy)

4. Start a company

5. Hire smart solid people

6. Work at your product for years

7. Become a public US company.