While we love these kinds of initiatives, unfortunately, we do not have a charities/non-profit partnership option for designers at this time and are not able to arrange a donation or special invoicing on your behalf. However, several designers who choose to donate their earnings to charities and other organizations do so on their own terms.
Some designers work with organizations to set up PayPal/Payoneer accounts to which the organizations have access. The designers then add these PayPal/Payoneer accounts in as their payment methods, directing all earnings to the organizations. Other times designers monitor their earnings reports so that they can keep track of sales, and subsequently donate any intended amount outside of the TeePublic platform.