> The problem is that enterprises have one mechanism to purchase software, and a totally separate mechanism for charitable donations.

And there is paid membership in business associations. That is closer to the purchasing department than to the donation department.

It really is a no-brainer: If there is an organization/foundation which supports the project, the enterprise could just join that, and may in turn even receive voting rights on the future direction of the project.

No need to make complex schemes to work around being unable to donate, or try to sell open source code.