Fireworks are typically on the starboard side on the Dream... not sure about the Wonder. If that is the case, you might not be able to see much from your stateroom balcony on the port side. However, post-covid they are doing fireworks twice on every cruise so that guests can be distanced on the top deck, with each party reserved a particular fireworks show. So if you have another adult in your travel party, you could take turns and one of you go to the top deck at the reserved time, and the other adult goes to watch the other fireworks show from deck 4. DH and I almost always trade off evenings with the kids. It's actually better now than when it was just one show, since we had to draw lots for who would get the fireworks before!
Edited to add--I originally wrote that fireworks were on two nights but I think it is maybe just twice in one night--the website just says twice. So I edited my post accordingly. Either way, same logic applies--taking turns should be possible.