Most integrations other than Z wave and zigbee are cloud to cloud, but you can write a service manager using rest end points. There’s no telnet support, though, so many people end up using a raspberry pi as a “man in the middle” local server.
You can see a number of those integrations listed in the “supported protocols” article in the community – created wiki, and that should give you a good idea of how people make those integrations work.