Raspberrymatic in homeassistant

Good morning,
I installed homeassistant yesterday on my synology ds 218+ in docker. I would like to have access to my raspberrymatic. I use homematic thermostats and they are all stored on an extra raspberry / raspberrymatic. Have also seen videos on the internet that you need an extra usb hm stick. Is that not possible otherwise, can not somehow share raspberrymatic for my homeassistant instance?
It doesn’t have to be the raspberrymatic either. I just want to have access to my homematic thermostat and window contacts without having to buy new devices.
Greetings Sebastian