Puncture resistance is a function of the tyre construction, rather than its size.
I'm not sure how puncture resistant the Kendas are on the Katu, no punctures on that so far, but I have had a couple on the AVE.
Tyre choice for 20" is more limited, but if you get punctures have a root around the Schwalbe website which rates each tyre for puncture protection.
Changing a tube is easier on a 20" wheel ebike because it's easier to manhandle the smaller frame and wheel.
I'm not sure how puncture resistant the Kendas are on the Katu, no punctures on that so far, but I have had a couple on the AVE.
Tyre choice for 20" is more limited, but if you get punctures have a root around the Schwalbe website which rates each tyre for puncture protection.
Changing a tube is easier on a 20" wheel ebike because it's easier to manhandle the smaller frame and wheel.