PNG08 height - EPSG:7447

WKT

VERTCS["PNG08_(height)", 
	VDATUM["Papua_New_Guinea_2008"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["PNG08_(height)", 
	VDATUM["Papua_New_Guinea_2008"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "7447"]]

Data from @esri/proj-codes

{
  "wkid": 7447,
  "latestWkid": 7447,
  "macro": "PE_VCS_PNG08_HT",
  "name": "PNG08_(height)",
  "wkt": "VERTCS[\"PNG08_(height)\",VDATUM[\"Papua_New_Guinea_2008\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"PNG08_(height)\",VDATUM[\"Papua_New_Guinea_2008\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"7447\"]]",
  "description": "PNG08 height",
  "authority": "EPSG",
  "version": "8.8(10.5.0)",
  "deprecated": "no",
  "areaname": "Papua New Guinea - 0~N to 12~S and 140~E to 158~E",
  "extent": {
    "slat": -12,
    "nlat": 0.01,
    "llon": 140,
    "rlon": 158.01
  }
}