There were several youth matches held at WHL which got 10,000 to 20,000 such as a couple in the now defunct NextGen tournament foir u19's. One of these was I think v Barcleona.
So I think a match v good opposition, maybe an NLD, at NWHL would get 20,000,
But agree those held at training ground only get a few hundred
I went to those. With the 1882 in full voice.
The west stand and I think south lower had people in them.
Nowhere near 10k. Maybe 3-5k tops.
Definitely not 20k.
Ladies would have same appeal if they get thousands going (I have no idea on their attendances).