Not that I know of, and what I’ve read of his fantasy isn’t very Conan. But proudly independent and warlike lost-colonies-gone-feral pop up semi-regularly in his short SF, and there are at least a couple of time travel/alt-hist stories that take a sentimental view of the proudly independent Celts, and there are the proudly independent sky vikings that pop up in a post-collapse story whose title I’ve forgotten... you get the general idea.