Adopting my cousin

I don’t know what I need here. If I need to rant or vent or advice. My Aunt has been secretly doing meth for the past 6 years. We have known about it for 2 years now. She’s been continuously making terrible choices. With virtual school this year my 9 year old nephew has been with my grandparents because they are retired, now it seems my Aunt has been getting harder with her addiction now that she doesn’t have to care for her son. It’s gotten to the point my grandparents are looking into temporary guardianship. I also want to put it out there that they paid for her to go to rehab this year and have tried to be supportive. This is not an easy decision and a lot of thought has gone behind them taking this step. My partner and I were talk about taking a step towards fighting for guardianship ourselves. Not that I don’t think my grandparents aren’t good enough for him but we know we can provide stability and emotional help he may need. I am 23 and my partner is 22. We do have one child together. I just want to know if I’m crazy for wanting to step up like this. I know I am capable. I know I love him. I know that I can love him like he is truly my child. My partner is all for it as well. Although we both wish that my Aunt could step up and be the parent he needs. She’s willing to sign her rights away at this point which is terribly sad. I just want what’s best for my nephew. He is the sweetest child I have ever known and deserves a loving parent more than anything.