My (non-US) sponsors want to know if there is an entity in my local country?

No, we don't register official Startup Grind entities around the world.

The proper/official way to do it is to tell the sponsor that we are registered in America, and that all payments and money and laws and tax and everything is managed by the American company.You create an invoice on our system, and then email the invoice to them. The sponsor simply clicks a link on the invoice and makes a direct payment into the account on said invoice.  Startup Grind HQ then handles the processing + tax + any other legal issues.

If they will not pay a US company you can also accept the payments through your own company and then add the income to your event invoice so the 20% goes back to HQ (you always need to ensure you pay over 20% of all money that is received).