Verify with the charitable organization that they registered to receive funds from Amazon!
Amazon's list of charities comes from GuideStar USA which compiled the information from the IRS, and includes organizations which may not have registered with Amazon and thus may never receive the donations. See the section "Charitable Organizations that Do Not Register" here: https://smile.amazon.com/gp/chpf/pd/ref=smi_se_saas_lpd_spd
Last I checked, there is no clear indication to consumers that a listed charity has actually registered.
The best way to verify this on your own appears to be to pretend you want to register that organization on Amazon's Org Central site[0] which will show if it's already registered. (An example search for Child's Play[1].)
As a shopper Amazon does not make this abundantly clear when you're selecting an organization. One thing to look for is the amount of information shown about the organization, specifically the incorporation year, as those that register have to fill out a profile.
According to the FAQ if a shopper selects an organization that is not registered and makes an eligible purchase they will track the donation. If the organization registers they'll get the donation, but if they have not after 2 years then Amazon will contact the shopper and give them 30 days to select a new charity. (I'm not sure if this then resets the 2 year clock or not.) If the shopper does not select a new organization then Amazon reallocates the donation across the registered organizations.
In any case the only way to be 100% sure is to inquire with the organization.
[1]: https://org.amazon.com/npo/search?q=Child%27s%20Play&p=1
I like the idea of SSH'ing with it, ill give that a shot.
https://support.google.com/accounts/answer/185833