Generally, papers can be submitted/requested to be submitted for open community peer-review on PhysicsOverflow using this thread:
Authors with more than 50 rep points can directly submitt their work, whereas the community will decide if papers of authors that do not (yet) have the rep needed to submit directly meet the scientific standard of PhysicsOverflow.
Concerning Vixra, it is perhaps known that there are many papers on that server that do not meet the standard of PhysicsOverflow. However, it is not impossible for a paper uploaded on Vixra to be accepted for open community peer-review here. It happend just recently.
I personally would love to see new collaborations and papers emerging from discussions on PhysicsOverflow, as it already happens on MathOverflow for example. In such a scenario, it might also be possible for people doing good work without currently being affiliated to a university/research institute, to find colleagues and co-workers who can help them advance their research here.