Normal emulator stuff. Games work, etc.
Linux support is slowly progressing, but really needs a strong contributor to fully support. macOS support is highly unlikely unless Apple gets Vulkan support.
There's a lot that could be done in the project, but there are many things that shouldn't be.
A lot of corners are cut for one reason or another: performance, lack of understanding, lack of documentation, etc. Getting something that perfectly matches the output on a real console isn't really possible with our approach. Conversely, this allows much more freedom to provide higher-quality or faster implementations.
Xbox Live Connectivity
Xenia will never be able to connect to the real Xbox Live network. A simulated Live-like network is possible, however anything that interfaces with the official Microsoft services is not only not possible, but not something the project seeks to enable.
Some multiplayer games are peer-to-peer, however many have some server component required for either matchmaking or actual session hosting. Though it'd be possible to work with such homebrew servers if projects sprung up to support them Xenia itself will not be attempting to do so.
Original Xbox Backwards Compatibility
Microsoft released a compatibility layer that enabled original Xbox games to run on the 360. Though likely feasible to get running under Xenia, it's not a goal. There's likely to be a lot of trickery going on that most games don't do, and distribution of the compatibility layer isn't possible.
Figure that out :)
Simulated Xbox Live Network
Implement the system APIs for friend's list, leaderboards, etc. Reusing Steam or some other service would be ideal.