I have this amazingly accurate switchbot hygro/temperature meter which you connect with your phone and you can set alarms for humidity.

But no space to put it in my AMS so i remixed this awesome spool holder from KYZ DESIGN to hold the sensor from the switchbot.

I use it with the hub and can set alarms for my humidity , it claims to be very accurate and appears also so , and a battery life of 2 years.

I like it a lot for it's accurate reading better than the local humidity meter with display which is less precise and has no temperature or alarms.

I bought the set from amazon but you can buy a standalone sensor and connect it with your phone but you will get no internet access without a hub.

I hope you like it , i know i do.

most deluxe set :   amazon  :    SwitchBot Wifi-thermometer, hygrometer, voor binnen en buiten, 4 stuks met hub 2, IP65 waterdichte temperatuur- en vochtigheidssensor met app-melding en gratis gegevensopslag : Amazon.nl: Tuin, terras & gazon

less deluxe set but also with hub :    SwitchBot WiFi hygrometer Thermometer 3 pakken met Hub Mini, IP65 Buiten-/Binnenthermometer, Vochtigheid-/Temperatuur-/Dauwpunt-//VPD-/Absolute Vochtigheidssensor met Slimme Meldingen, werkt met Alexa : Amazon.nl: Tuin, terras & gazon

or a minimum but without internet connectivity  : SwitchBot IP65 Buiten Binnenthermometer Hygrometer 3 Stuks, 120m Bluetooth Bereik, Koelkast Thermometer, Dauwpunt/VPD/Absolute Vochtigheid Sensor, Gratis Data Opslag Export, 2 Jaar Levensduur Batterij : Amazon.nl: Tuin, terras & gazon

even one single piece is available    :    SwitchBot Indoor/Outdoor Thermo-Hygrometer | Temperature Humidity Monitor | SwitchBot EU (switch-bot.com)

Let me know your feedback.