I’m working on a temperature logger for refrigerators and room temperature.

At my wife's work (Pharmacy) they are very dependent on that they are within the limits of the law and must document any high and low temperature and an alarm would be nice. This is a work in progress; so many things have not been decided yet.

Would to consider:
It should fit in a small case.
How about the sensor - outside or inside box (will it be warmer?)
Sensor precision vs price vs calibration
Calibrate sensor in software
Transmit either via lower band radio or by WiFi.
Does radio use less power that WiFi?
Range from within a refrigerator?
Interference from other devices?
If radio, another device must receive and then transmit by WiFi.
Battery operated. LiFePO4 (can drive an esp8266/32 direct) or Li-ion (more capacity but needs a voltage regulator).
Processor battery usage? Deep sleep measurement.
Onboard charger or separate charger
Web page for the data. Local Raspberry Pi or cloud?
What CMS? Drupal? MQTT?
App for the alarm or SMS or email?

Many of these would need some good test equipment and mine is somewhat old and can’t quite keep up.

Illustration is one of my test, that needs work!

The board:
MCU with transmission capabilities, temperature sensor with digital readout and range from -10 to 50 or so Celsius. Button and LED for setup. LED also for status/errors. Battery with/without voltage regulator.

Thanks for this possibility!