I can rectify the connections between Howard and Lovecraft pretty well here.

Its not too far of a stretch to say that Conan stories and Cthulu stories are in the same universe. But the stories are set in a way to not influence one another in any major way. Conan being king of Aquilonia doesn’t influence the decisions of a character in early 20th Century Call of Cthulu any more than some weird aliens do Hour of the Dragon.

Where darthphysicist is correct though is we are viewing the story primarily through the REH lens as far as what is canon and what isn’t. And any particular objects, places, or people referenced from Lovecraft are just what Howard would likely do, friendly nods to similar out of story ideas.

I wouldn’t take those references as hard foundational canon, and more of as homages.