Also can get it from a can of chickpeas. The liquid already in the can is aquafaba
Also for best results, looking up “[dish] aquafaba recipe” will often work a bit better than 1:1 substitution because it can sometimes benefit from slight ratio changes of other ingredients. Though 1:1 substitution will still work
Have to say, his post has probably got to be up there on most successful blog posts of all times. We’ve got a whole Wikipedia article with 29 citations because of it and tons people actually using his suggestion