The /discourse status command currently lists the subscriptions for all channels.
But /discourse follow tag:foo only applies to the current channel.
As a Slack user, I don’t want to sift through a wall of text to look for the subscription status of my current channel. I just want to know what my current channel is watching.
I don’t think there needs to be a slack command to show the subscription status for all channels. Admins can always look at the plugin page to see the complete status.