Welcome to the forum! Kinda scary how little grease is in a sealed bearing. I haven't done the fronts yet but a wheel-on check seems good. I bought all 5 bearings and seals + 1 extra of each for around $100.00
OM
They do don't need much grease. To much grease and they will run hotter. Adding grease give more chance of contamination. What you add may not be compatible with what is already in the bearing.