I've found some posts and looked through related issues (hinted from this post: https://intellij-support.jetbrains.com/hc/en-us/community/posts/115000784044-Sphinx-with-PyCharm), however, I'm still unclear if there is any support for auto complete.
For Sphinx, it would be great if there was some kind of auto completion for :ref:, :class: and similar.
I'm in the process of working out how I want to structure my documentation (not just doc strings, but detailed docs) and we already use Confluence a lot (which makes things like tables and links to other pages super easy). I'd love to have something similar in PyCharms with Sphinx at least for cross referencing documentation (code too would be great, but that's lower priority).
I'm interested enough that if the feature doesn't exist, I might try develop it as a plugin, but wouldn't mind some pointers to doing that.