cups
cm
Grams
Centimetres.
UV
They'd probably use millilitres.
gallons
cups
You would use the metric unit of meters to measure the height of a gallon of milk.
liters or milliliters or cups.
The unit of measurement for milk is litre (L) in the SI.
cups
Litres and parts of a litres is used to measure milk.
You would use a millilitre or, equivalently, a cubic centimetre. A larger unit, which could be used, is a litre.
Probably centilitres.
A "can of coconut milk" is not a unit of measure! However, to give you the benefit of the doubt, had you said "How many deciliters in a 400ml can of coconut milk" then the answer would have been 4.
Anything under a quart I measure in milliliters.