Thank you for responding. After playing with the code some more, this ended up working for me:
import arcpy, os
outputLocation = r"C:\TEMP"
aprx = arcpy.mp.ArcGISProject(outputLocation + "/VTPK.aprx")
m = aprx.listMaps("VTPK")[0]
basemap = m.listLayers("Basemap")[0]
for filename in os.listdir(outputLocation):
if filename.endswith(".vtpk"):
lyr = m.addDataFromPath(outputLocation + "/" + filename)
m.addLayerToGroup(basemap, lyr)
aprx.save()
continue
else:
continue