I'd say go for it, it could end up being really fun for you. :3

Writing fanfiction can be quite the labor of love. I used to write a lot back in the day but lately I've been mentally struggling with life and all that it's hard to continue with the stories I have in limbo. The best piece of advice I can give from years and years of personal experience is if you really want to bring this story idea, fanfiction or otherwise, then you really have to put in the time to do it. Instead of binge watching videos or playing video games, set some time away from distractions towards this story and baby it with attention on and off.

Try not to do it all in one go, that can easily burn you out and lose pace and focus. If you do end up getting at a spot in the story where there's not a lot of action and you can't figure out the flow, try something similar to those multi-choice books or tabletop roleplay the scenario where dice numbers represent an action and see how that goes. Sometimes random and unexpected can have a interesting effect. Pacing is definitely something to stick with as you don't want your readers super excited all the time and wowie so much going on and no breather omg another action Boom! Action scenes can lure your readers in, slow and calm scenes can give them a breath and anticipate the next action.

Another good thing to do is write down all the major plot points you want to write in your story and then fill in the gaps with smaller action scenes, calming scenes, suspense, maybe some hidden lore, whatever it takes to get from major point A to major point B. Then hopefully with some luck and time, you'll have yourself an amazing fanfiction to share :)

I hope any of this helps and I look forward to if and when your story manages to come to fruition!

Dunno if it really matters coming from some rando (who's also learning creative things and somewhat running into a wall), but I think ya should do it (just to give another supportive voice on the subject). Even if it doesn't turn out great (personally or in terms of general response) for whatever reason, the attempt and learning experience is fairly important in itself when it comes to figuring out writing. Valiax especially has a lotta good ideas in particular, though I'll definitely stress that that the learning process/feel can be pretty different from person to person. It's hard to find your own personal sense of comfort when doing something new, but I think you can find some personal writing space that's good AND satisfying for you for sure.

(edit: uh, sorry if this is a bad response, just felt kinda compelled to respond ;~;)