Can I support a pledge with my Giving Account?

Grant recommendations can be made in support of non-legally binding pledges. Accordingly, you may tell charities that you "intend to recommend a grant from your donor-advised fund in the amount of [$]" so they know your grant recommendation is being made in response to a charitable organization’s request for a commitment.

When submitting a grant recommendation online, once you confirm that the charity does not consider your pledge to be legally binding, select “Pledge (non-binding)” from the grant use menu.

Read this article for more information:
Can I make a pledge with a donor-advised fund?