Itch by default keeps only 10% which is already low, Steam keeps 30% in comparison.
Going below 10% would be immoral, although technically possible. Considers that Itch must pay for all the infrastructure that allows having the website and downloading the game, in addition to processing the payment.
VERY IMPORTANT, it is not 30% of all transactions, only 30% of transactions made from the USA.
Creating a business in the USA prevents Itch from WITHHOLDING that 30%, but it does not exempt you from paying taxes in the USA, the difference is that you will have to present documentation of your company's profits to the IRS and pay the corresponding taxes. Doing this whole procedure is complex and costs money, it is recommended that you do it if you are really going to have a company that makes good profits, if you are only an independent creator, it is not worth it.
You could apply for an ITIN, but I couldn't tell you what benefits or penalties there might be over using your country's tax ID.
In order to request a payment from Itch, you must complete the tax interview where it is mandatory to present your tax identification. There is no way around this.
Plus, you have a 3 dollar fee for validating the tax interview.
Example:
10 from USA - 30% tax - 10% Itch - credit card commission = 5.5 10 from Germany - 10% Itch - credit card commission = 8.5 Total = 14
PS: The balance shown by Itch is only an estimate, you have access to the final and detailed value only when you request payment from Itch.
PS2: An alternative is to use the direct payment system. But you should keep in mind that with this system, you are responsible for setting up payment methods and dealing with taxes, since each person who buys your game will be doing business directly with you and not with Itch.