Incorrect explanation

[AbdSattout]

However, the >= operator in fact works in a very different way, which is basically to take the opposite of the < operator

That's not ture, >= and <= operators just convert both sides to numbers if they have different types and that's why null >= 0 returns true because 0 == 0 is true.

You can test that withNaN and will return false :

NaN == 0 // false
NaN > 0 // false

// But ...
NaN >= 0 // false

You can see that NaN < 0 returns false and >= operator doesn't return the opposite.

So >= and <= operators are just shorthands :
x >= y → x > y || x == y
x <= y → x < y || x == y
and if x and y have different types they will be converted to numbers before comparing.