If you wanted to get rid of the moister absorber for a less maintenance approach there are Peltier dehumidifiers on Amazon for about $20 to $35. It's simple technology and easy to build your own with a few parts to embed it in the humidor wall.
https://www.amazon.com/Portable-Dehumidifier-Dehumidifiers-Humidity-Basement/dp/B0BBVD3FBR/ref=sr_1_31?crid=1OF3M5W1ZOAI2&keywords=small+peltier+dehumidifier&qid=1684785836&sprefix=small+peltier+dehumidifier%2Caps%2C116&sr=8-31
If you hold a Peltier wafer between your fingers one side gets cold and the other side warm depending on the DC voltage sent to it. With a few volts/amps it can freeze water on one side and boil water on the other side at the same time. The wafer is about a 1/4 inch thick. The bad part is moving the condensation it collects to a drain and sizing the heat sinks without adding moving parts like small computer fans and pump.
If you wanted to get things really fun, you could incorporate a Arduino or Pi with motion, Bluetooth, wifi modules/shields and temperature, humidity sensors. Your humidor could nag you in a good way by sending you emails or phone text your cigars are safe and to enjoy one at certain times.
Sadly, I just can't add a USB port in a car without relays, voltage controls and battery packs. It would bug me until I figured out a way to rattle the walls with the THX soundbite to that humidor door and lighting effects as I approach it.