That's not correct. Sig Sauer USA's VP of Engineering Adrian Thomele was originally an Sig Sauer AG employee, who owned a company that was acquired by Sig Sauer AG. There are other examples of engineering management propagating from the German/Swiss entities and sharing IP between one another. Secondly, Sig Swiss AG recently announced that they would be manufacturing the P320. The German entity was shuddered to decrease manufacturing costs and effectively offshore to Sig Sauer USA, who is now also offshoring more manufacturing operations to India. I think there is much less independence than you might think between the entities.
Some more history you might find interesting - Thomele & Mayerl designed the FCU and P250 that would ultimately be the foundation for the P320. Thomele then went onto some of the design work for the P365 from my understanding while the P320 was going through trials and having issues. He's been in numerous depositions along with some of the US engineers that report to Thomele now like Sean Toner.
