I noticed in the API the Piglins do not have any methods specific to them, but the Piglins have some interesting stuff.
Missing things:

• Age/Baby state (important)
• Zombification immunity ( If set to true, the piglin does not transform to a zombified piglin when in the Overworld.)
• CannotHunt (If set to true, the piglin does not attack hoglins.)
• Time in overworld (The number of ticks that the piglin has existed in the Overworld; the piglin converts to a zombified piglin when this is greater than 300.)