I personally don't like this whole sponsorship thing. This sets up people to optimize for getting and retaining sponsors instead of doing things that they would have wanted. A better approach could have been to offer money o fix issue or implement feature. For example, you could file issue/feature request on a project where developer has indicated that they have no time to work on and then offer $1000 to fix it. This is small amount if you depend on it for your business. The developer can decide if its worth their time and interest.