designing load for the MCU to drive by output current
Yes, if you connect an MCU output directly to one of these inputs and nothing else, the output current will be 1 &micro;A or less. The MCU pin functions as a voltage source, and the current is determined solely by the load.

And 1 &micro;A is much less (20000&times; less) than 20 mA, so there's no danger of overloading the MCU pin.