Adopting a child from the state

My cousin had 4 children with 3 different fathers and they were all taken away from her due to being an unfit mother or addicted to drugs. Well my mom took her youngest a 2 year old boy. We grew up with him. He’s lived with us since I was about 14/15. I’m now 23. My mom sadly passed when he was 5 and he went to my uncle after that. Well my uncle is extremely unfit to care for him. He doesn’t make him brush his teeth, he feeds him crappy food so he’s overweight, he has a couple health problems. He needs bifocals because he’s practically blind without them, he’s on ADHD meds, and he has two cochlear implants but he speaks just fine with help or a speech teacher, and can hear just fine. He is a smart kid and makes good grades. My uncle is just spending the money the state gives for him and when he’s 18 and goes to college he won’t have money for a car or for college if he doesn’t get a scholarship. My husband and I are 22/23 and he’s in the military. We will be moving on base in a 3 bedroom house next week. We have a 12 month old son of our own. My husband is all for adopting him, or even just being his guardian so we still get assistance from the state because we are still trying to get ourselves financially stable. I mean we do just fine, own our own cars, have health insurance, have everything we need. We just want two very good incomes. I’m a SAHM attending college. I feel like I can take this on. The boy is now almost 10 and he’s not bad, he listens if you discipline him correctly. My sister is 26 going on 27 this year and refuses to take him even though she has no kids of her own, and has graduated college and is an accountant. She initially agreed to take him next year and has since then gone back on it because his health is getting worse because of my uncle. I can’t sit here and not do something about it. I just have no idea if I should being that I am so young. Would it be wrong of me to take him in? I mean I know I could give him a more structured life. Idk what to do in this situation or even how to go about it. Any advice would be welcomed.