I have found sensors of air purifiers to be better than DIY or standalone ones. Dyson and Xiaomi have local endpoints which can be used to access data without a

I have found sensors of air purifiers to be better than DIY or standalone ones. Dyson and Xiaomi have local endpoints which can be used to access data without access to internet. Home Assistant makes the process of collecting and storing data easy with HACS and some plugins. You may also try Tuya based solutions which maybe flashed with ESPHome but they mostly use DHT11/14 based sensors and need some soldering. Another approach is using a BLE based sensor and then using a BLE to WiFi bridge to get the data into HomeAssistant or similar product which can log the values.