OpenHAB abstracts all of your devices. So your light switch can directly interact with Spotify , or your tv input can influence the color of your Philips hue bulbs. I know that is not a good example but it exemplifies the integration between different objects you may want to automate. This is native, you can also do scripting to support custom actions as well, which is based on JavaScript. Then you can build many different uis. You can have the home assistant-esque UI or you can build your own ui complete with custom css and js to give a completely unique interface to your automation environment.

Also notifications aren’t locked behind a paywall with openHAB. OpenHAB cloud is free, or you can launch your own OpenHAB cloud container and self host notifications (assuming you get the relevant Apple/android api keys)