I tried following your instructions for a couple of Unity games I own on Steam, Hades and Back to the Dawn (with a mod to support discord rpc). It didn't work, likely because the name of the pipes being connected is wrong. I'm looking at the file https://github.com/Lachee/discord-rpc-csharp/blob/master/Unity%20Example/Assets/Discord%20RPC/Scripts/Control/UnityNamedPipe.cs#L219 and I think the pipe name is supposed to be "snap.discord/discord-ipc-*", where * is the number of the pipe, usually 0.