I don't think that SSI is anymore a creature of the state than is SSDI. It is federal. To get it, you have to have the same eligibility as for Social Security, that is: you have to be either over age 65, or completely disabled from working. (But, as you say, Gus, you don't need any credits. You don't need to have even ever worked at all.) Once you are over age 65, or disabled in the eyes of the SSA, all that counts is your income/financial need. Is it low enough and are you poor enough?

You can have 10 doctors certify you as disabled, and that's great to have, but that does not make anything automatic. You have to go through the same process as you would to get SSDI. You apply in the same way. You have to fill out 13 pages of questions about why does your diagnosis interferes with you working at anything. (And they don't care about weather there are any jobs available in the economy.) You have to convince them that you are not likely to recover anytime soon. It's a hard case to build, when you consider how many people with significant disabilities do manage to work at productive jobs. It's especially hard to make the case when you are young. They will ask what effort you have made to train for something that allows you to work around your disability.

The truth is that, historically, most people do eventually get a lot more out of Social Security than they ever put in. That is particularly true for people who get out on SSDI. (It will likely be true for me.) It will be less true for people younger than me. And it will get less and less true the younger you are. The program is getting stingier.

SSI replaced the old state programs that used to be the main source of support for the impoverished old, blind and disabled. SSI is totally federal. Individual states do supplement SSI for beneficiaries. That is to say, your state may give you something extra once you get SSI. But the state has nothing to do with determining your eligibility for SSI.

There is cash assistance that you might be eligible for. You'ld find out about that by going to your local income support office. That's the place where you apply for food stamps. This is a state administered affair. They look at your household circumstances.

Do look into applying for food stamps and housing assistance. Food stamps is one of the easiest things to get, though not if you live with people who have a good income.