US Credit unions and community banks don't work with IBCs. You'll need to go and apply in one of top 5 banks. Or find a EMI.
Have a US EIN for your IBC and intend to deposit 250K for a USD-only account. Multi currency corporate banking does not require more deposit, but is only available from 2.5-5M annual turnover, for example in Wells and PNC. EastWest bank offers multi currency to SMEs, but they stopped accepting IBCs. Could be an option for a US LLC though - make your offshore IBC own the US LLC for this banking option.
The US slashed interest rates recently, and due to "lack of reward", getting a bank account there is not as easy anymore for non-U.S persons.