Up until you said.... real time.... natural sounding...

I did find a few by searching.... how natural it sounds is, I guess, totally on your ears and how critical the listening environment is.

I saw a band many years ago that swore they were using s harmonizer, controlled by midi, to do the BGHV for their live show. I couldn't tell you the name of it if my life depended on it. That was over 30 years ago and I'd almost guarantee they were lying to me and they were running a tape.

But... here's a link to the supposed 10 best: https://www.sustainpunch.com/vocal-harmonizer-pedals/ there are a few videos of them in real time action. Fairly impressive.


You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.