Former bank employee here. You don’t need a squirt gun. Theoretically you can walk into a bank, tell the teller you’re robbing them and demand $1, then sit patiently on a bench and await police. The problem is that the judge at your sentencing will see that you are not truly a danger and give you probation. You will also have to pay fines.
Bear in mind that prison is not free. You are charged every day you are there, and will receive the minimum care to keep you alive.
The best option is to get a bus ticket to a part of the US with fewer homeless folks and good safety nets, then get a social worker. They will require that you don’t have any living family who can help, so bear that in mind.