Many fruit trees take years to bear fruits. For example, apple trees can take two to seven years depending on their rootstock, and up to around 10 years if seed grown. Another interesting example is Monkey puzzle trees as they take between 30 and 40 years to start producing!
One advantage of the air layering propagation method is that you can root branches old enough to have fruit spurs. In this video, they successfully rooted a 3" thick maple tree branch! https://youtu.be/p1z7O4JQOIA?t=45
Let's say I air layer a tree with the right ages of fruit bearing branches, would it be able to bear fruit immediately?