Indeed, Maimonides presents a different perspective on this matter, and this is his language in the Laws of Blessings (Chapter 11, Law 15): "He takes the lulav, blesses 'Al Netilat Lulav,' since he has raised it, he has fulfilled his obligation. But if he blesses before taking it, he blesses 'Le'tol Lulav,' like 'To sit in the Sukkah.' From here you learn that one who blesses after performing, blesses on the action, etc., and so he blesses 'Al Biur Chametz,' whether he checked for himself or for others, because once he has made up his mind to nullify, the mitzvah of Biur Chametz is fulfilled before he checks, as will be explained in its place." That is, before he began to check, the mitzvah of Biur Chametz was already fulfilled by deciding in his heart to nullify it, and therefore it makes sense to bless before the check 'Al Biur Chametz,' as the mitzvah has been fulfilled.

At first glance, it requires clarification, as it has not been nullified or removed yet, only he has decided in his heart to nullify it, and how has the mitzvah of removal already been fulfilled. It needs to be explained according to the words of the Ramban and the Ran that the essence of nullification is not removing it from his possession, but that he no longer considers it chametz in his eyes, but as dust, and it has lost all value in his eyes. Thus, from the words of Maimonides, it is well explained that once he made up his mind to nullify it, the mitzvah of removal was fulfilled, even though he did not say anything, because in his mental decision, he already considered the chametz as dust in his eyes and it was deemed as dust, fulfilling the mitzvah of removal.