You can teach her whatever you want if it's helpful for her future. It is also is really up to the kid and the intellectual level she is at. There are kids where you think they are there years ahead of the time. The issue I see is how her environment would deal with it. Kids tell a lot and her teachers might find out that she is already in touch with cryptocurrencies. What if one teacher sucks and is old and depressed and against crypto, might make fun of her or not assess fairly.
Good luck to you and your daughter and have fun!