BrandMeister maintains a Last Heard list. This is a real-time list of all activity on the network.
You can find the list heard page at https://brandmeister.network/?page=lh
The last heard page shows all activity worldwide. You can open the search panel and create a filter to restrict your view to a single master, repeater, talkgroup, call sign, radio ID, and a few other things.
On each row, you may notice a speaker icon in the Destination column. This is a link to the Hose allowing you to listen to the conversation.