I have a low power project with three NO push-buttons and a SPDT toggle switch. Each contact is monitored through polling by ATtiny I/O pins with 1 meg-Ohm pull-down resistors, the 5V VCC is passed by the contacts. For the prototype I've thoughtfully selected switches with gold contacts rated at 0.4VA, but the selection and availability is very limited.
My question: Is it necessary to have gold contacts here?
The 5 µA is nearly nothing for the contacts, silver contact resistance of 10 or even a 100 Ohms shouldn't matter with 1 meg-Ohm pull-down resistors.