Both branded and unbranded virtual tours are available for syndication to IDX and other 3rd party sites. However, while it is available for vendors to access and download, each site chooses for itself whether or not to display the virtual tours. Just attaching a virtual tour to your listing does not automatically ensure that it will appear on all IDX/3rd party sites.
The MLS has no influence over what information sites choose to display. We make the appropriate data available to them, but it is ultimately their decision what they want to display.