With Kolide portal's right sidebar with OS groups, is there aconfiguration change to add another OS group? For example, what if I wanted another distro other than Ubuntu?

Click "add new label" and you can create a query that will generate groups of hosts.

Is there any way to convert my tag into platform option? I want to set my queries to cerrltain tags where Linux is only Ubuntu.

You can target a pack to a label

Gotcha