Potential Bloodborne Crossover

So, I'm thinking about potentially making a crossover fanfiction between Bloodborne and Demon Slayer with Tanjiro as the Hunter (I'll figure out how he gets into Yharnam before the series starts, if I can get an answer that's satisfying enough).

My question is twofold;

A) would siderite (the main material used in the trick weapons of Bloodborne) and quicksilver bullets work on demons? I assume the quicksilver would at least halt the healing process of demons considering it's liquid mercury infused with infected blood (the Hunter being moon-blessed and their blood being mixed with the blood vials of Yharnam), and siderite is able to kill literal gods.

B) if siderite and quicksilver bullets do work, then would Tanjiro still have to go for decapitation, or would hacking away at them until they can't heal work? Because if he can just hack at them, he'd be able to prevent them from healing and getting away until the sun comes up, or separate them to the point that they can't regenerate properly. The only demon I can recall that has extreme regenerative ability to come back from almost nothing in a fast pace is Muzan, but there was also demons who could grow back whole limbs, and even heads given enough time.