In most cases, there shouldn’t be a need to separate topics based on the platform. Perhaps the one major exception for this is in #bugs-and-issues and in some #self-service:wishlist topics.
For this reason, the forum team has added two new tags for our use pc and xbox. In Bugs and Issues, you are required to provide at least one tag when creating a topic, and those tags are the ones that come up.
For more information on using tags, take a look at this: Forum Tags.