No, a guitar with a normal (conventional) pickup cannot be directly used with the Roland GR-55 Guitar Synthesizer. The GR-55 requires a guitar equipped with a special divided pickup, like the Roland GK-3.
The GR-55 uses advanced guitar modeling and MIDI conversion technology that requires separate signals from each string. A standard pickup produces a single output that combines the vibrations of all strings, which is not suitable for the GR-55’s polyphonic processing. The GK pickups, however, provide individual outputs for each string, allowing the GR-55 to accurately track pitch, dynamics, and string bending for precise sound synthesis and modeling.