I have been trying out MQTT on a Meshtastic node here in Connecticut USA. I quickly found out that using the default topic msh/US causes problems. I have to agree doing this is like drinking from a firehouse.
I have found out that there are regional topics. For example, the MQTT topic msh/US/CT is for Connecticut. My suggestion to other Connecticut MQTT users to use the msh/US/CT topic. This way , one does not have to look at the Meshtastic Node Map to find other users and then filter the node database for a specific node to try to contact the node. I think this approach would help to grow the number of nodes in Connecticut. As always, I hope this is a help to others.
Yes, WB1ELG, the official node map shows only a little activity. I have found only two places with significant activity. The first is Middletown with the node Sunpeater. It is about 20 minutes from my home with no direct connection. When I want to test something then I drive to it a good location (Wendys in Portland). I can usually connected to Sunpeater and a couple of other nodes. Unfortunately, none seem to be on MQTT.
The second location is Litchfield, which is about 2 hours away. It (Great Acres Farm TF&G Router) is associated with a farm. There are several nodes there. There is a MQTT connection under the topic of /US/GAF.
I also occasionally see nodes on aircraft passing. I have see a node in Glastonbury briefly.