For the humidifier I've got a typical 1 bedroom ultrasonic one from Amazon, but anything will work so long as it's an always on one that won't mind having power cut via the controller. For the dehumidifier, I've got a large one that's intended for a decent sized room, so that's definitely overkill, but I got it on clearance for $40 instead of the normal $150. I would imagine something like what I link below is plenty for a small fridge.
https://www.amazon.com/dp/B07KF6Y19V/ref=cm_sw_r_cp_apa_glt_fabc_QWKZESHT0C474ZCK21PH
A little more expensive than I remember, but not terrible.
The one I have doesnt have any indicator or use a desiccant. I have something like this:
https://www.amazon.com/dp/B07KF6Y19V/ref=cm_sw_r_cp_apa_i_CuCmFb84R6ZE7