Sounds to me like it would about as useful to have some kind of self-certified checklist for themes: how much testing have you done, are you ready to receive reports on quality and security, will you be responsive to feedback.
Or indeed, what is your development process, in no more than three sentences.
The truth-value of the responses won’t be worth much, but the difference between themes which are self-certified and those which are not might be a signal worth something, to the person thinking of installing the thing.