Unless you have a Snapdragon 865 or newer (Galaxy S20+ or newer), the Extra Quality build will stutter. Stick to the "Lite" version for mobile.
Because these are unofficial fan projects, they are not available on official stores like Google Play or Steam. They are typically hosted on community platforms:
Demon Slayer Mugen V8 is a fan-made fighting game that brings together characters from the Demon Slayer universe, allowing players to engage in intense battles with their favorite characters. The game is a part of the Mugen series, a popular fighting game engine that enables creators to develop and share their own games. With a vast array of characters, stages, and gameplay mechanics, Demon Slayer Mugen V8 offers an engaging experience for fans of the series.
M.U.G.E.N is a freeware 2D fighting game engine designed by Elecbyte. It is famous for its limitless customizability. Fans can import character sprites, backgrounds, and UI elements to create their own "dream matches."