Thanks @NiccoloGranieri. In fact, it turns out that it is, indeed, possible to make anonymous submissions with PubPub. See this test article that I also mentioned in the PubPub thread.
What is nice about OSF, though, is that it allows for storing all sorts of other stuff together with papers (since it is a bucket-based system), complete with DOIs. At the moment, it seems like we cannot have it all. But to summarize:
- PubPub could give us a strict and multimedia-rich template with very nice reviewing/commenting features.
- OSF could give us a solid, bucket-based solution, with DOIs, but would not solve the template problem.
So I am leaning towards PubPub > Zenodo being the overall best solution.