Display temp humidity and ventilation recommendation

I would like to show in every room on a small display the actual temperature, humidity and a ventilation recommendation which is calculated by a OpenHab Rule regarding the outdoor conditions.
In the moment I have in every room a homematic sensor without display. I would like to change this or add one more display which can show these three statuses for the room:

  • actual temperature
  • humidity
  • a ventilation recommendation

I’m using in the moment Zigbee und Homematic infrastructure.

The goal is to always now quickly if I should open the windows or not.
In the moment I get warning via Alexa if I open a window and this doesn’t optimize the room conditions. But this is no nice solution because I like to no this before I open the window.

Can I show the extra ventilation recommendation on any Homemantic Temperature Sensor? Or do you have any other harware recommendation for me?

I am still looking for a cheap solution.