This isn't answering your question, but I'll share my experience. Mum bought me a razor when I was about 11/12. I shaved legs and underarms until I was about 18. Then I had my first wax and have been waxing for over 20 years now. I have a lot of body hair normally, so it took about a decade of waxing to thin it out.

Waxing hurts. I may be used to it, but it still hurts. That's something I choose to do for myself so I can go 3-5 weeks without stubble. I also pay about $130 every 6-8 weeks for this. It's expensive and it hurts.

I have also had IPL to reduce pubic hair. I am now trying to grow back some of the bush because I've changed my mind about a bald bikini line. I have been struggling to grow back overplucked eyebrows for about 5 years.

My opinion based on my experience is, buy her a razor, show her how to use it properly and let her try waxing in her own time and when she can pay for it. Teach her not to overpluck her eyebrows. If she wants to shave everything off, it's her body, her choice. I'd just leave the waxing until later.