While we do receive requests for a Mac version from time to time, we're currently focused on Windows based machines, as this speaks to the core of our customer base.
We do have an open feature request for an X1 Mac version, however no release is imminent at this time.
In the meantime, although it's officially ‘unsupported’ by X1, there are a decent number of X1 users (including some X1 employees) who search with X1 via programs that run Windows programs/applications on a Mac, such as:
Please note that X1 will only run in a Windows environment and will not be able to index or search your Mac apps or files, including but not limited any Office apps for Mac (i.e. Outlook for Mac).