Its hard drive, optical drive, power supply and heat pipe have separate guides; model revisions matter for power parts.
What to check before buying
Hard drive and optical drive
iFixit has separate replacement procedures for the hard drive and optical drive. A game install problem and a disc-read problem should not be priced as one part.
Cooling and power
Power-supply and heat-pipe guides are also listed. Identify the PS4 Pro's CUH revision before choosing a replacement supply.