So this thing is essentially an IR blaster with a temperature sensor + other sensors?
Generally, I'd recommend capturing the cloud traffic while you still can. Including the procedure that joins it to your Wi-Fi network!
This will make things much much easier for you.
Check if it is encrypted at all. If not and if there is no magic authentication mechanism that uses secrets on the device, you might be able to mock the cloud quite easily.
If it is, check if it's implemented properly. Does it use HTTP? Is it HTTPS? if so, does it validate certificates correctly? Can you just give it something else? A self-signed one? A valid one for a different domain?
Does it use something self-built with static keys?
If that fails, the next thing to do would be to take a look at the hardware.
The Ambi Climate Mini 2 looks the most hackable of their products as it comes with an ESP32 and tooling for that is readily available. Maybe it could run Tasmota?
https://valetudo.cloud/
https://www.reddit.com/r/homeautomation/
Maybe it can be solved with a simple firmware patch.