I have an open PR that adds support for particles and cosmology to the Enzo-P frontend. https://github.com/yt-project/yt/pull/1490...
All tests are passing and the documentation should be up to date. If you have any interest in this functionality, I would appreciate it if you could take a few minutes and look this over. It should be ready to go.
Accompanying this are two new sample Enzo-P datasets available from yt-project.org/data. If you'd like to play around with this, I suggest getting those.