This is basically whats happening in every research lab/center. Researchers are working towards the next funding period, meaning they have to impress the people who grant those budgets. The result orientation of research labs isn't what people think it is. The result they are working towards is funding, first. The result they are working for is getting regular paychecks in for a longer period.
So we know this is a billion dollar idea, and they only need 5 mil. Rikens budget is like 800 mil/year (I think). So what you'd do first is try to get money from the Riken pool, obviously.
Now perhaps this years money is already spent/planned with, although it's hard for me to believe that they wouldn't be getting the money immediately when the payout is so large if you could convince the people who allocate the budgets at Riken with actual hair grown on a human. You'd be surprised how quickly 5% of a yearly budget is suddenly available when you have a promising billion dollar idea. At the very least, they should be getting this money 2022, and tbh they should be getting it if their idea even had only a 5% chance of working.
So the problem is that they are not convincing for Rikens internal expert panels allocating the money. There is no way some scientists who produce results are like "yep, lets ask for donations for a cosmetic issue instead for money from our firm".
You don't need advertising through a call for donations. That's just unprofessional. Shocking, really. Grow hair on a human being, and the whole world is looking at you.
Another day, another hair loss money grabbing strategy.