IANAL and this is not legal advice, but it is a tactic I've seen used to distribute cannabis in places where possession has been legalized but it is still against the law to sell [0]. I'm not sure if it is still being used anywhere.

In this case, it would be more of a polite fiction, as I don't think anyone is seriously going to take action against a charity effort.

0: https://www.google.com/search?q=free+cannabis+gift