Quantifiers realised by a noun?

This type of string is often called a pseudo-partitive construction. (A true partitive looks the same, but shows a partition, a subset: a half of the money, a piece of the cake.)

From an article by in linguistics by Ilja A. Seržant:

Definition of pseudo-partitive constructions

A pseudo-partitive construction (abbreviated: a pseudo-partitive) is a partitive construction with no specific superset in the restrictor.

While the true-partitive relation implies proportional quantification, pseudo-partitives denote plain quantification such as

• amounts (a group of people),
• measures (a cup of tea) or
• quantities (a lot of people, a majority of people)

of particular kinds (people, tea). Therefore, pseudo-partitives are sometimes referred to as quantitative partitives (e.g., Ihsane 2013).

These obviously grade into collective nouns. The article strongly suggests that all pseudo-partitives are quantifiers. But I'd separate out definite measure phrases (a kilogram of sugar, a litre of blood). Interestingly, 'a spoonful of caster sugar' in a recipe book is more likely to be a measure phrase, 'spoonful' being a defined quantity (ill-defined, as there are various conflicting definitions). But used loosely, often deleted to 'two sugars, please' say, it's a quantifier [+ noun], with 'spoonful [of]' being used in a rough, quantifier way.