Indeed. DC resistance is only a measure of how long the wire is versus its diameter if you took it off the coil and straightened it out. It really means nothing by itself regarding output. The factors that determine output are type of coil, geometry of coil, diameter of wire, type and gauss of magnet, polepiece or rails interaction, proximity to the strings, pole piece versus coil proximity, etc.
DC resistance is measured in ohms, usually kilohms for standard high impedance pickups.
Output is measured in AC millivolts for passives, and even as high as volts for actives, when the pickup signal is induced by a standard source.
Finally, all modern amps have input gain and active/passive circuitry. The actual output of a pickup doesn't mean much anymore, as it can be adjusted on the front end, unlike older amplifiers, like original Fender Bassman or such.