I bought a similar small peltier style unit because my very large whole house style unit was too big. Mine (and yours) do not have an adjustable shut off point like my large one does, however I wouldn't worry too much. These only pullout less than a cup of moisture per day, more like quarter cup if that. For me it was enough to lower my humidity from 60-65% to a much better 45%. I leave it on all the time and it never goes lower than that.
Humidifiers work better when humidity is high, and decrease in efficiency as humidity gets low. I don't think a unit like this would ever reach even 20-30% before it got to a point where it just can't get anymore water out of the air.
Here's the unit I got: Ivation ERSDM18 Mini Dehumidifier with Both Peltier and Exclusive Ers Technologies for Power Efficiency and Better Moisture Removal https://www.amazon.com/dp/B00RZVHB7M/ref=cm_sw_r_cp_apip_gfKd6xoEncN4I
Humidity: I have taken one of these
https://www.amazon.com/Ivation-ERSDM18-Dehumidifier-Technologies-Efficiency/dp/B00RZVHB7M
And broken it down to the internals. It fits perfectly inside a 4 inch pvc and should work well.
Pictures coming with the next update.
For cooling im using this
https://www.amazon.com/dp/B01J1S15UK/ref=cm_sw_r_cp_apa_z0woAb2CW5CQE
But it won't arrive for a few weeks.
I was planning on making one myself with liquid cooling instead but this was much cheaper. I'm already spending more than I imagined lol.
For co2 I'm considering this sensor
Everything controlled via raspberry pi is the goal. But it is all a distant goal for now.