Blake and Mortimer (although more pulp than punk) especially Secret of the Swordfish.
In Franco-belgian comics, Tanguy et Laverdure or Yoko Tsuno would also qualify, both available as translationBlake and Mortimer (although more pulp than punk) especially Secret of the Swordfish.
I hope someone else has made the same point, but being aimed at kids isnt really something that makes something not serious. A lot of childrens entertainment is handling serious topics so much better than adult entertainment that adult entertainment has branched into its realms. Think Bojack Horseman, which is a weirdly amazing insight into the habits that form a cycle of self destruction and the desperation of trying to find something to fill the void that will never come. Its no suprise that it features characters who are anthropomorphic, ex children entertainers and who have names like "princess buttercup".Okay, "The Iron Giant" is a great flick, and it's definitely in the right timeline...but it's still aimed at kids.
The two suggestions so far have been sooooo close, but with at least one insurmountable deal-breaker.
I strongly suspect that what I'm looking for really doesn't exist, that if it's going to exist, I'm gonna have to be the one to make it.