It's not really a summer hassle you can fix with a miracle solution, I'll be honest. Special music, pheromones, natural supplements... that works for some dogs and does absolutely nothing for others. Your labrador has real anxiety, not just a normal reaction, so you need to get ahead of it rather than wait until July.
What I'd suggest is starting well before fireworks season. Create a safe space in your home - like an interior room with no windows, or a corner with blankets and stuff that reassures him. Get him used to staying there for several weeks before it starts, without forcing him. During that time you can actually test out pheromones (it can't hurt) or even check with your vet to see if some light medication for a few days makes a difference. Some vets prescribe anti-anxiety meds for the critical periods - it's not the end of the world to give him that for a few days in summer.
The other important thing: ignore his panics as much as you can when they happen. No "poor baby" petting, no dramatic reactions - that reinforces his stress. Stay calm, let him hide in his safe space, and go about your evening normally. Over time and with experience, some dogs learn it's not a real threat. It takes a few summers, but it's possible.