Fastest? If you are not against KYC, then use River.com it happens in a few days (is that fast?). Here is a referral link cause I’m shameless: https://river.com/signup?r=TPLHHAEN7M
Discussion
In this case, I am against KYC. It’s cash right now, I’d rather it not go through the bank.
Prepaid cards or cash app (kyc) is the quickest but I haven’t done a prepaid card before.
I have not done that yet. I see a few ATMs around that say they convert cash to bitcoin. But I have never felt real comfortable with those.