Buying US T-Bills/Treasuries

The yield on US treasuries has gotten very high. Im wondering if anyone buys them from NZ? What are the transaction costs like? What do people think of this as an option for parking some cash insetad of just TDs in NZ? Anyone doing it?

Stock and bond percentages are a common strategy in the US for various reasons but in NZ we dont seem very on top of it. How about using US treasuries from NZ if there is a cheap and feasible option?