The problem I try to solve Looking for a temperature sensor using Bluetooth that can report to Home Assistant through my phone when out and about and preferably (but not necessarily) report through my ESPhome BT-proxies at home.

Background I have a 3 year old son with type 1 diabetes. As a result I always have to carry insulin, a temperature sensitive medication. The vials are stored long term in the door of my fridge together with a ZigBee sensor monitoring the temperature of the insulin. If it freezes the Insulin denatures and won’t have any relevant effect if used. The vial that I carry with me will last for around a month as long as it stays above 0 °C (and under around 25-30 °C). My son uses a CGM/pump-based system, creating a BAN that also involves his smartphone. This means that phone is always near the vial and could record temperature (and send telemetry data) continuously, even away from home. I want to use a temperature sensor to identify spoiled medication due to thermal conditions even when my son leaves our home.

My current (imperfect) solution I currently deploy a solution where I use a Meshtastic node with a BME280 sensor. It reports through the mesh to a node at home. This node uses MQTT to talk to Home Assistant. The problem with this system (although nice being totally independent from the Internet) is limited coverage of the surroundings as well as very infrequent telemetry reporting to not overload the common mesh in my city.

Is there an easier solution? Preferably one that uses the smartphones bluetooth (BLE?) and reports back over the Internet.