@WakerOfWinds i heard of fanfiction.net it probably would be good for you, since your story is fantasy, but its a fanfiction foremost.
Eh i gotta be honest with you, that is my same feel with fanfiction.
I also want to go to places where there's less fanfiction of already existing original work, and see more originality with stories. I want to find originality, not some 54 variations of Harry Potter or Sasuke when I can just read the one true original and canon one...
Unless that existing story kinda sucks or leaves a lot of questions, (i've seen some stories that makes me feel like i want to write a fanfic on just to put more depth/closure into characters).
Why not make your own original characters and stories instead of basing it off another's existing story? Forget about using other characters and worlds. Eventually you'll write so much, your story might completely go on a different path that you can't even tell what it was a fanfiction of and the only thing they have in common would be the name. Why not just remove the shared names and storylines and turn it into something completely new then? (Look at Cassandra Claire, 50 Shades of Grey, and the After Movies)...
It'll save you a lot of pain when you want to monetize it, cause monetizing fanfiction, regardless how much you wrote through your blood sweat and tears, is still monetizing a story that's off of an existing story/characters done by another author.
Sorry I kinda ran off-topic here. Coming back to the thread's discussion...
My take is to just write and put it out there bud. No matter how it feels to be kinda out there writing fantasy on platforms that are more geared towards romance, isekai, etc. You'll never know until you put your whole effort in and see how many readers you get.
Maybe you'll make a break into it and you'll start the next trend of SH fantasy fiction. That's what I'm plan to do - just write it out and see how much traction it gains - since I don't think my stories necessarily fit the popular tropes on here. But I'm just gonna push it out and see what happens. Maybe it'll open new boundaries for stories. ;)