Do I need a special compressor for filling a PCP?

Yes. PCPs need 3,000 to 4,500 PSI, far above what a shop compressor produces.

Dedicated airgun compressors range from $300 entry-level Chinese units (Yong Heng, TUXING) up to $2,500+ premium units (Air Venturi Nomad, Alkin W31). Entry-level compressors need active water cooling, regular condensate purging, and frequent filter changes. Run them in short cycles to avoid overheating. Do not try to convert a paint or shop compressor - they cannot reach airgun pressures and are not built for breathing-quality air.