How would I do that?
My current code is: KEY_UNIT_OF_MEASUREMENT: "ºC",
Also, I believe the correct Unicode character is 0xba, not 0xb0.
I checked Mosquitto output to see exactly what Core2 is putting out. It's very strange. When I add the 'degree' symbol, the JSON is missing a closing parenthesis (which is why HA is complaining). I'm showing you below the Mosquitto output for the temperature sensor and the humidity sensor. Both are formatted in the same way. The temperature sensor has the degree symbol.
homeassistant/sensor/core2/core2-temp/config {"avty_t": "~status", "pl_avail": "on", "val_tpl": "{{value_json.temperature}}", "dev_cla": "temperature", "unit_of_meas": "ºC", "~": "core2/env2/", "dev": {"mdl": "Core 2", "mf": "M5Stack", "name": "Core 2 Thermostat", "ids": ["12234"]}, "name": "Core2 Temperature", "stat_t": "~state", "pl_not_avail": "off", "uniq_id": "12234"
homeassistant/sensor/core2/core2-humid/config {"avty_t": "~status", "pl_avail": "on", "val_tpl": "{{value_json.humidity}}", "dev_cla": "humidity", "unit_of_meas": "%", "~": "core2/env2/", "dev": {"mdl": "Core 2", "mf": "M5Stack", "name": "Core 2 Thermostat", "ids": ["12234"]}, "name": "Core2 Humidity", "stat_t": "~state", "pl_not_avail": "off", "uniq_id": "122347"}
And here's the same Mosquitto output, when I remove the degree symbol.
homeassistant/sensor/core2/core2-temp/config {"avty_t": "~status", "pl_avail": "on", "val_tpl": "{{value_json.temperature}}", "dev_cla": "temperature", "unit_of_meas": "C", "~": "core2/env2/", "dev": {"mdl": "Core 2", "mf": "M5Stack", "name": "Core 2 Thermostat", "ids": ["12234"]}, "name": "Core2 Temperature", "stat_t": "~state", "pl_not_avail": "off", "uniq_id": "12234"}
homeassistant/sensor/core2/core2-humid/config {"avty_t": "~status", "pl_avail": "on", "val_tpl": "{{value_json.humidity}}", "dev_cla": "humidity", "unit_of_meas": "%", "~": "core2/env2/", "dev": {"mdl": "Core 2", "mf": "M5Stack", "name": "Core 2 Thermostat", "ids": ["12234"]}, "name": "Core2 Humidity", "stat_t": "~state", "pl_not_avail": "off", "uniq_id": "122347"}