Man, I wish I could give you a definitive list, but the truth is the 'wolf mermaid' niche is incredibly specific and mostly lives in the realm of indie romance web serials. I’ve seen maybe one or two Kindle Vella stories that tried to mash a wolf pack alpha with a selkie or siren myth, but they weren’t very good—the worldbuilding felt forced, like they just slapped a tail on a werewolf and called it a day. The power dynamics between a land-based pack structure and a sea-based hierarchy could be amazing, but most authors seem to default to the mermaid just becoming part of the pack on land, which defeats the whole 'blending' aspect.
You might have better luck looking at 'monster romance' tags on sites like Amazon or Scribblehub, where the blending is more about the creature than the setting. 'The Mabon Feast' by C.M. Nascosta is about a goblin and a werewolf, nothing oceanic, but it shows how indie authors are playing with myth combos. For the sea element, maybe try some 'kraken romance'? Those often deal with a human or otherworldly character being brought into a deep-sea society, which has a similar 'clash of worlds' feel.
Honestly, if you find a good one, let me know. I keep checking, but it’s a lot of duds so far.