I think that would change the balance of power dramatically and ensure fast and effortless conquer of the Promised Land.
For those (interpreters and those of you) who hold that the conquest had to be "natural", by the power of force - battles, and wars, why didn't G-d reveal the secret recipe for gunpowder?
I think in the eyes of the nations that would surely raise the Israelites in the rank of G-d's people.
Besides for the fact that G-D could have helped the Jewish people conquer Israel using 'natural' methods in a quicker manner without giving them futuristic technology, the premise of the question that G-D wanted Israel to have a 'fast and effortless' conquest is also mistaken.
Devarim 7:22 explicitly writes that G-D wanted the conquest to be slow and gradual:
וְנָשַׁל֩ ה"א אֶת־הַגּוֹיִ֥ם הָאֵ֛ל מִפָּנֶ֖יךָ מְעַ֣ט מְעָ֑ט
לֹ֤א תוּכַל֙ כַּלֹּתָ֣ם מַהֵ֔ר פֶּן־תִּרְבֶּ֥ה עָלֶ֖יךָ חַיַּ֥ת הַשָּׂדֶֽה׃The LORD your God will dislodge those peoples before you little by little; you will not be able to put an end to them at once, else the wild beasts would multiply to your hurt.
The simple explanation for this (said by Rashi and others) is that if Bnai Yisrael captured too much of the land at once, their population would not be large enough to fill all the land, and wild animals would come in to fill the void.
God didn't give the Jews a super weapon because he was the super weapon.
The covenant with the Jews is that if the Jews keep the Torah, God will protect them. If God gives them all machine guns with unlimited ammo, they don't need God to protect them because they could just massacre all of the Canaanites, Philistines, Arameans, Assyrians, Babylonians, and Egyptians within a month.
God wants the Jews to be dependent on Him so they will always serve him.
A simple answer to this question is that Maimonides felt that G-d never instructed Israel which was contrary to our state of development at that time. This could be applied to gunpowder and is applied to animal sacrifices, in which he felt that G-d did not want nor need but that people felt that this was the best way of worship. See Ben Shapiro regarding this. Now to the long answer.
Although the Torah commands to conquer Canaan, Moshe Rabbeinu sought peace, which was the true goal of the Torah. The Torah teaches to treat non-Jews fairly, as we ourselves were once slaves in a foreign land. More than forty times Israel is commanded to love its neighbors. See (Leviticus 25:35). Rabban Yochanan ben Zakkai gave blessings of peace even to pagans. See (Berakhot 17a). And Rabban Gamliel passed out bread to a pagan he never knew simply because he was in need of food. Refer to (Eruvin 64b). We are even encouraged to visit non-Jews and pray when they are ill. (Shulchan Aruch, Yoreh Deah 151:12) and (Tosefta Gittin 3:13).
Thus, G-d, who is transcendent, would not reveal gunpowder (which will be invented a few thousand years later by the Chinese in the 9th-century). True, the Torah demands the conquest of Canaan, but Moshe saw that Torah's ultimate purpose was peace, and realized that this was placed because Israel needed to hear the call to arms at that time, but when a close examination is applied, we find that Joshua never "conquered" or destroyed the inhabitants of the Canaanites against their will but gave three options, a) leave peacefully, b) convert, or c) fight. While some chose to fight out of free will, we cannot call this a genocide as the land was promised to Abraham and his descendants, and Joshua proposed a peaceful solution. To call this an act of aggression or genocide, you can not.
PS the term "genocide" was invented only a long time later, and no one regarded the Bible as a "book of genocide." Not to mention that the word genocide and the concept of genocide is alien in the Hebrew language of the Torah. Thus, there was no need to reveal gunpowder. And if there were, one could speculate why not reveal nuclear power or biological weapons. Because the goal of Torah is peace, not war.
Could be this would answer your question.
וכתב הבניהו בגיטין (דף סח.) וז"ל יש חוקרים שלמה המלך ע"ה היה חכם מכל אדם ועשה כסא עצום ונורא המבהיל בדמיון ועוד כמה וכמה מיני חכמות,ואיך לא היה יכול לעשות חכמה זו של שמנדפי"ר [רכבת] לעשות מרכבה של עגלות ההולכים במרוצה ע"י אש כעוף הפורח,
והשבתי להם בודאי ידע חכמה זו ועשה אותה, אך לא עשאה לתשמיש בני אדם אחרים כי לא רצה שתתפשט חכמה זו בעולם וילמדו אותה גם האומות לעשותה, כי צפה ברוה"ק שאח"ז יבואו האומות בבל ויוון ואדום וילחמו בישראל, אך מחמת שמקומם רחוק לא יוכלו לבא על ירושלים בקלות כנשרים אלא צריכין להתעכב בדרך זמן הרבה וכאשר ילחמו בישראל ויפלו מן האויבים של ישראל חללים ויצטרכו להביא חיל מעירם להוסיף על חיל שלהם לא יוכלו לבא במהרה ומה דביני ביני יהיה הצלה וישועה לישראל ואם היה עושה זה למהלך רבים היתה נודעת לכל העמים והיה יוצא היזק לישראל בדורות הבאים כאמור על כן עשה זה המהלך ע"י אש בעגלה אחת וכו' שלא יהיה נודע מעשיה לרבים וכו' ונראה על זו העגלה וכו' קרי לה שידתא כי שידתא לשון שד כלומר עגלה זו הולכת במרוצה גדולה כמו שד ושידה, כי השידין יש להם מהלך קל מנשר וכהרף עין ילכו מקום הרחק יום אחד או יומיים" עכ"ל
The question seems arbitrary, but this much is certain: If the Israelites had gunpowder, the rest of the world would have discovered the recipe soon enough and primitive, idol-worshipping societies would have destroyed any hope of progress in the world, especially since there were so much fewer people in the world at that time to begin with.
