There might be allusions to the Hiroshima/Nagasaki bombing should the Island land over the capital, and just how most post bombing stories involve the survivors picking themselves back up, Momo will rally the people that Wano can be rebuilt as long as it has people.
		
		
	 
 
hmmm
I already  think the explosion  should  occur  at least as fake hype  fir act 3 end.
Like this onigashima  explode  in air above the capital act 3 end,
act 4 we see onigashima  destroyed  to parts  and kaidou flames are gone , the capital  people  are running  away from the falling  rubbles.
Momonosuke  save  citizens by making  some rubbles float  , also otger members of SHs and samurai  are saving  citizens. 
onigashima  side almost everyone is ok but they already fallen  in the capital
thanks to zoro he cut the explosion  before it destroy  everyone.