Hi,
I’ve experience in writing MQTT discovery for several projects to implement auto-discovery down to icons and suggested area names. There’s a few posts on this forum on this matter, so I’d suggest a few links and the forum search.
Do you have an idea, how the MQTT message could look like in my special case?
It looks like several hot beverages of your choice 
, the documentation, the above examples, and several prototypes you publish and experiment with something like mosquitto_pub!
It’s not as hard as it looks; it just takes a few tests which happily give instant results in HASS giving a very fast debug-cycle (HINT: delete retained topics to remove test data to clean up afterwards).
If this helps, 
this post!