This NUR repo contains up to date versions of Ryujinx, yuzu-mainline and yuzu-ea. These packages take quite a while to compile, so I've set up a binary cache using cachix.

First of all, you should install the NUR.

Afterwards, enable this repository's binary cache. This hosts a precompiled binary of all packages.

nix run nixpkgs.cachix -c cachix use ivar

After this, you can start a shell with any packaged emulator, which will always be up-to-date.

nix-shell -p nur.repos.ivar.{ryujinx,yuzu-ea,yuzu-mainline}

Alternatively, in your home-manager configuration, put the following:

let
  nur = import (builtins.fetchTarball "https://github.com/nix-community/NUR/archive/master.tar.gz") { inherit pkgs; };
in {
home.packages = [
  nur.repos.ivar.ryujinx
  nur.repos.ivar.yuzu-ea
  nur.repos.ivar.yuzu-mainline
];