This seems to be something people don't always give second thought to. When people talk about the homeless, the first things thought about are images of people on busy city streets in rusty clothes waiting around near allies. In there, the answer is quite static, because it can be I guess. But if that's the case, change the setting and that changes too. In the places where I've lived, people often needed that mapped out. Where are they known in your rural locales?
There are many social programs, but the biggest one is "Expense assistance", where the state will make sure you have minimum amount of money required for living after income. In practice it's around 600-1000€,just enough for the cheapest rent and cheap food. However that's all you need to get back on your feet.
Its calculated after income, so you will only receive the bare minimum needed for basic living. However if you want to live in a small apartment with no actual disposable income there is nothing stopping you. Thats actually how some students get by.