Yeah, vocaloids are literally just an amalgamation of sounds to create voice-like sounds. Not all of them sound robotic, though; there's one in particular that comes to mind by the name of Wotamin. I've only ever heard one song by her, Rubik's Cube, but she sounds pretty realistic.
And there are a few AI singers that I've heard of. I know there are robot singers, and, if I'm correct (it could go either way), there are AI recreations of real singers. They don't have anything on the level of what you see in media, of course, but I'd give it a few years. It doesn't seem too far off, especially because Japan exists.