In principle, medically necessary care is available for all persons who need this in the Netherlands. COVID-19 services are covered by the Health Insurance Act, although patients have to pay the mandatory deductible (as in normal medical specialist care) when admitted to the hospital. No other out-of-pocket expenditure is applicable.
There is a need for more sheltered places for homeless people (https://nos.nl/artikel/2328371-leger-des-heils-wil-aandacht-voor-daklozen-in-tijden-van-corona.html).
Undocumented migrants can receive care from hospitals that have a special contract with the Ministry of Health. In emergency cases they will be admitted to the closest hospital where beds are available. Undocumented migrants have to pay for the care out-of-pocket, but hospitals are compensated by the government when costs cannot be recovered from the migrants. This is similar to non-COVID-19 related care.