You can't get financial aide if you don't have a HS diploma or GED. That route only works if you can pay for your classes yourself. But it's actually common that you can't get a degree until you have that high school equivalent done. So if you went for nursing, you wouldn't get your degree until you get your GED. What can help you, though, is a lot of community colleges offer programs for your GED that can actually get state grants to get you through it. Or your state probably has programs to get it for you.
Most nursing programs
outside of extremely competitive areas, are only going to look at what you did at that school. I failed out of college once with a 0.4 GPA, I never went back to retake those classes, and I'm in nursing school, because I did really good at this school I'm in now. So, getting into school and getting that nursing degree is never impossible. It depends 100% on the school though, typically an associates from a community college is going to be your easiest bet, but to graduate and get your degree, they'll typically require your GED. And getting into nursing school is competitive. You can be the best student, but if it's between you and someone that graduated high school or has their GED, you're the one getting cut. They need to see that you're going to finish. Their accreditation depends on it, enough people have to complete their degrees every year. You definitely want it before you apply for nursing, regardless of your school's rules for admission.
So while you technically CAN go completely through nursing school without your GED, you're not eligible for financial aide. That's federal law. BUT if your local schools accept people without their diploma or GED, you might be able to get that while you're working on your prereqs to apply for nursing. It's probably going to take you over a year until you can even apply, because odds are, you don't have the prereqs to the prereqs that you need. You'll probably need some developmental classes since it's been so long. So expect that if you can get started in the fall, that it'll take you 4 years to finish your associate's degree in nursing, and you'll probably have a second degree finishing up around the same time if you stay full time. From needing every class at a developmental level, it should take you about 3 semesters to be actually done with all your general education classes at most community colleges.