I don't think there is anything wrong with being a sissy.
But I would not consider myself a sissy even though I like to wear pretty girly clothes. I love to hunt and kill animals, build, lay bricks, climb trees, dig in the garden, mountain bike, rock climb, tatoos, body piercing. I'm tg, but I am not a sissy.
Can you have sissy girls? Don't know if it applies. As such I don't think the term could apply to mtf or us non-binaries can it?