how do I calm my dog during thunderstorms?

hi! i’m fairly new to training a dog so would appreciate any advice!!

My 1+ year old pup has suddenly become very anxious during storms. He doesn’t mind rain but he is triggered by lightning and thunder. He paces around during rain but does frantic zoomies into the rain while barking non stop. He will bark for the full duration of the storm(eg. 2-3 hours).

Ive tried to calm him down by holding him during the storms, wrapping him tightly in towels, creating a dark and dim enclosed space to calm down in, giving him chews to redirect attention. But nothing seems to work particularly well .

When the storms are less severe, he calms down in the dark enclosed space + he chews the treat and doesn’t bark. But on days where storms are heavier and the thunder can be heard indoors, even with all windows and doors closed, he goes off pacing and barking.

I wish to avoid sedating him with medication if possible. I have bought a noise muffling head wrap, yet to try. So if that has worked for anyone’s dog do share your experience 🙏

I want to try desensitising him to loud noises, if anyone has any pointers I would appreciate the help! ( how long does it take? what to avoid? is it possible that desensitisation fails?)