I had a thought while reading your closing statement. A lot of men currently in tech, the ones who are allies of diversity I guess you could call them would probably be more than happy to help mentor some of these aspiring women in tech as well. It may not be as effective as a woman mentor whose been there, but it could help pick up the slack if done correctly.
Even better if it’s say organized and mitigated by a woman in tech. Where she could answer gender related questions (like how to deal with sexist attitudes) while the male mentor could just help with the more technical and basic career related questions, that and have their backs when/if trouble happens. You know go all big brother on the jerk who tries to harass them.