OK, so no shade on your idea, but you actually can tell your dog he is OK.

Using a loud voice is a good indication that there is a threat or play, one of the two. Using a super quiet voice, such as a whisper, can convey the opposite. I have worked with a bunch of dogs and the most effective thing I have found for reducing barking and panic is to whisper their name with a positive tone and get down low enough for cuddles and petting.

They tend to look at me confused, tilt their head, then eventually stop barking and come over. I then give them quiet praise and lots of petting and cuddles as per their preference. Over a fairly short time they tend to shift to a short set of barks to announce the threat followed by coming to me to seemingly verify my attention to the issue, then they settle down.

This is mostly with either family dogs, 5 of those, or client's dogs, another bunch to varying degrees.

Also, I would recommend Training Levels: Steps to Success by Sue Ailsby. I have used that book for a lot of dog and cat training and honestly it also works with how I interact with kids. Clear communication, lots of praise and love, capturing behaviours and associating them with words, and never ever using negative stimuli like hitting or yelling. Or as I see it now, respect. Dogs are intelligent beings and if you try to find your common communication tools you can be much more effective at sharing your needs and getting their buy in. Same with kids, actually listening to their needs and observing their behaviour gives you a massive step up, and then never ever being mean or unsafe and always being safe and protective can take you a long way.

I'd tell my cats I'm not chasing them to hit them (I've never raised my voice or hit a cat), I'm just walking that direction. You don't have to run like a bat out of hell. And no, no voice works like it does on dogs.

He knows by your voice and demeanor. He 100% knows when you're panicked and bases his response from it if you're bonded enough. If you're chill, he's chill and will learn. Dogs are amazing.

Give him yummy treats like yak cheese sticks when it's crazy so he can associate loud noises with snacks and time with you.

The fact he needs you to help him deal with things he doesn't understand is what makes for a strong codependent relationship.

If he could talk you would hear more poop jokes than the human mind is meant to handle.

What you really want is for him to understand you.

Have you considered a thundershirt for him?

Even if you could, it's an existential threat. Thunder for Dogs is the equivalent of Cthulhu for us, but it actually happens all the time.

I've read before that dogs can achieve a level of intelligence of a human four year old (or thereabouts).

So your conversations with your dog would sound very monotonous and tiring after a few years. It sounds cute at first ... but after telling your friend "everything its OK" for the thousandth time after ten years ... and you still have to explain things ... it would get pretty tiring.

You might actually be able to help him. There are trainings you can do to help a dog get used to sudden loud noises; hunting dogs for example get this training so they can work around gunfire. No reason it wouldn’t work for things like thunder and fireworks too.

I bet if you did talk to him in a calm, soothing voice, and told him he was safe and that it won't be forever, it would help. Dogs get a ton of cues from our words and demeanor even if they don't understand exactly what is being said.

If you want to see how well your dog can communicate with human words, you could get him a soundboard. It's a relatively new area of research as far as I know but it looks like dogs have at least some facility with them.

My current golden is smarter and better trained than my last. Thing is she just does not have impulse control when she has something she likes so like can't keep her from jumping on people. Its like if anythig is within 10 ft of her obeying goes to zero. Really its like she would want to but all the brain juice just clears everything away. The other thing is she absolutely hates noises she can't determine the cause of. She does a bit better if I open the balcony and sit with her there but the further away we are the worse she gets. Its like with dogs. one is barking and snarling in her face. no prob. one is barking from a balcony and she can't pinpoint where. run away! run away!

Give him human-like speech but all he can say is stuff like "bark", "woof", "ruff". Understands a handful of our languages though.