I am a great fan of teaching girls (and boys for that matter) fighting skills.
Teaching fighting skills should be part of the school curriculum IMO
Learning how to finght is great fun, it excellent fitness training and it teaches kids respect and disipline.
For children boxing really is a great choice because it teaches kids discipline, hard work and respect for teachers. It also teaches kids how to fight back if they are in danger. Also Amateur Boxing Clubs (ABCs) are inexpensive and many do great work with kids diverting them from crime and teaching them how to behave properly.
Judo is also good as the training is standardised and so you are less likely to encounter a martial arts cult or McDojo.
tae kwon do is excellent for exercise but may be limited in terms of martial applications in a situation where a child needs to defend themselves.
My knowledge of TKD is limited as I have not trained it myself, however I know many people who have. There are 2 main schools of TKD and both are very foccussed on kicks generally and high kicks in particular, which may not be the best way for a child to deal with a real life opponent.
ABCs that teach juniors often have single sex classes, so my suggetion would be for you to check that out once we are out of lockdown.
I also think that, whatever MA your daughter learns, it is in her best intersts when the times is right, to spar with male opponents. Sparring is friendly, controlled violence and is great for helping females to learn how to hit males very hard in the face and body (obviously pads are used).
Also good boxing and judo classes will help kids understand the limitations of their skills.
I have seen lots of not very good martial arts trainings for women and children where the instructor imparts a false sense of badassery onto students, potentially placing them at risk of harm.
Due diligence is important