Rotary handle sensor

for my automatic blind control I would like to have a rotary handle sensor installed on two doors.
So far, I have found only those from Homematic, for which there is also a binding for OH3.
As I understand it, you have to buy for these sensors also mandatory a “central”, with which the sensors communicate. Did I understand that correctly?
Is there any other alternative? Because I’m not sure how useful this central is, if I want to implement only these two sensors with it…