I will be traveling to Israel this summer, which uses 220V power instead of the U.S.A. 110V. I am aware that my DSs need a voltage converter, but my Apple products don't. Do I need a converter for my Nintendo Switch?
You will not need anything more than a physical adapter. The Switch charger has printed on it, "Input: 100-240 V~ 50/60 Hz 1 A", indicating that it can work with any input voltage between 100 and 240 volts AC, at either 50 or 60 Hz.
Do verify that your own charger has this printed on it as well, just in case. There might be different models.