Can girls who have not reached the age of puberty and have memorized five parts of the Qur’an lead prayers?

The preponderant view is that it is permissible for a boy to lead the prayer, both supererogatory (nafl) and obligatory (fard), if he is the most knowledgeable of the Qur'an among the congregants and is well-versed in the rulings of prayer. The same applies to girls leading other girls in prayer, or boys leading other boys. The term "boy/girl" here refers to one who has not reached puberty, not one who has not reached maturity.