Every time there is an effort by the anti religious forces in Eretz Yisroel to attack Shabbos, kashrus, the kedusha of the Kosel Hamaaravi, etc, the anti religious leaders warn the government that if they resist, they will “alienate” the Jews of the diaspora, by which they mean American Jews, who they assume to be overwhelmingly secular and liberal. In reality, we know that although the frum Jews are still a minority of Jews in America, we are not a tiny minority like we used to be, and we are much more likely to have visited Israel and care about Jews in other countries (see the 2020 Pew study of you doubt this).
A large turnout of frum, and especially chareidi Jews at the march could help dispell this dangerous myth, and will בע”ה help our brothers in Eretz Yisroel see that America is full of frum Jews who care about all Jews everywhere and are willing to come to support them.