Just setting up a charity as an Amazon affiliate will get it around 5% of purchases made through the affiliate link (see here)
And charity credit cards are, of course, a popular idea.
Apparently Amazon shut down use of the affiliate program for charities and are now pushing AmazonSmile.
'MIRI' works in the search field when electing a charity to get 0.5% of your https://smile.amazon.com purchases.