As already mentioned there is no &&=
-operator thus you can´t overload any. For a list of operators you can overload for any type see here. For assignement-operators there are no overloads defined at all:
Assignment operators cannot be overloaded, but +=, for example, is evaluated using +, which can be overloaded.
So your current approach using myBool && Foo();
is the way to go.
As mentioned on this post the IL for &=
and &
are equal making the former just syntactic sugar of the latter. So there´d be no real value on creating such an operator as all its use would be to get rid of a few characters.