General rule for current flow in op amps?
You can reasonably assume that currents can flow from an input (Va in your diagram) and from the op-amp output (Vo in your diagram). This means you can assume current does not flow into the two op-amp inputs and these can be regarded as high impedances.

Additionally, you can assume the op-amp open-loop gain is very high and the impact of this is that for an output voltage that is reasonable (i.e. somewhere within the bounds of the power supply rails), the difference between V1 and V2 is zero volts.

All the above assumes that there is an overall negative feedback that keeps the output in the linear region i.e. within the bounds of the power rails.

If the overall feedback is zero or positive then the output will likely be end-stopped against one of the power rails and there may well be currents taken by the inputs AND, you can no-longer assume V1 = V2.