Yes. I assume you’ve read the docs to create MQTT sensors?
Something like this should work for value_template:
value_template: "{{ (value_json['devices']|selectattr(1,'equalto','30AD2A354CDE')|list)[0][2] }}"
That should return the third element (RSSI) for the first item matching that 30AD... MAC address. The 1 in the selectattr statement is reading the second element in the list item and comparing with the hard-coded MAC address. The template tool is great for homing in on what you need: just work iteratively:
