The term of art for this is "discretionary income". I think it is a more informative than disposable income, but it is much harder to find for many countries. The US Bureau of Labor and Statistics (BLS) publishes surprisingly detailed statistics on consumer expenditure at decile resolution which allows it to be easily computed.
Discretionary income is defined as disposable income after you subtract housing, utilities, food, clothing, healthcare, and transportation costs based on actual survey data. Roughly speaking, discretionary income is the amount of money available for saving or spending on fun. If you want to know the mean and distribution of how much a person spends on eggs or fresh vegetables in each decile, the BLS can tell you that. It also tracks a lot of non-essential expenditures. It is a great resource.
Discretionary income is defined as disposable income after you subtract housing, utilities, food, clothing, healthcare, and transportation costs based on actual survey data. Roughly speaking, discretionary income is the amount of money available for saving or spending on fun. If you want to know the mean and distribution of how much a person spends on eggs or fresh vegetables in each decile, the BLS can tell you that. It also tracks a lot of non-essential expenditures. It is a great resource.
Here is the combined report from BLS for 2018:
https://www.bls.gov/cex/2018/combined/decile.pdf