I'm tempting to do this, I have a almost-finished app but need help to end and release, however, look like doing this is giving away too much, and I have not see how pull-back from assembly if later in the road I need it.
They could very well take projects in varying stages of completion and provide services, and maybe the costs can be worked out or something.
Reaching out to them and asking how they handle your use case (someone with like 80% of a project done who really wants help for a final push + release), should be education for both parties.