Well the first is that the statue of Liberty which is literally supposed to represent freedom and justice was destroyed by guns.
The second I caught was that the age devil will only die by the sacrifice of children. Symbolizing that the people who cling to power(eternal life) do so by killing the children of the future. And with Denji being fed that blood, even those who oppose such a practice need it to live due to the system set up.
But that's only what I caught on my first time reading.
and also add the fact that this is most likely a critique of the United States government. with Makima, Fujimoto criticized the Japanese government too, and now with the presence of a Devil who is in contract with the USA government who can kill from such a huge distance... it really is a critique of USA imperialism too.
You can't miss the symbol here :'> fujimoto is cooking with all these metaphors