Will God punish American citizens if the United States of America does not illegalize homosexuality?

Yes.

We see that in Sodom and Gomorrah, God rained down sulfuric acid on the whole city and killed all the citizens, including those who did not personally practice homosexuality, because the cities allowed homosexuality to proliferate.

God’s Law is clear.

Homosexuality must be illegalized.  Homosexuals must be arrested by the police and other law enforcement agencies of the state (FBI, Homeland Security, National Guard, etc.).  Homosexuals must be executed for crimes against nature, crimes against God, and crimes against humanity.

When a nation does not illegalize homosexuality, God will punish that nation.

You can read Isaiah and Jeremiah to see how God punishes nations.  Of course, punishing nations means that God will send calamity down upon the citizens of that nation.

Thus, when God punished Israel as a nation, God allowed Israel’s enemy the Babylonians to come and conquer Israel.  Millions of Israelites died in the conquest.

It is clear that when God punishes a nation, God’s justice impacts the citizens of that nation.