The main issue is that a bunch of vertices are pinned (red dots in the uv view) and thus cant be moved into the bounds of the texture. Just select everything in the uv editor and unpin them using right click -> unpin.
The other seams look good, but there are 4 edges missing - one near the foot, at the lower body and on the eyebrowns.

If you add seams there you can use the regular unwrap to give each surface its own paintable uv space. (apply the mirror modifier beforehand unless you want symetric textures)

File: https://blend-exchange.giantcowfilms.com/b/EkSV3sJA/