Just added second option to the right but placement would also be under nose. First is pretty easy, just a stitch.
Second would be a little loose stitch and then securing it in a curve (I’ll get a video if I find one soon but ribblr is glitching a little for me at the moment)
It could be pink to match the nose or maybe black but that would stand out a lot
I think your bunny turned out super cute ! ^^ for mine, I just made a sort of “T” shape for the nose and mouth (though I think it made my bunny look a little more like a dog ). If you do update the mouth, I’d love to see it