Yeah, it’s (SimpliSafe) a closed system. It is easy to set up and use for what it is, but it’s definitely not made or marketed for real home automation.
I actually like their monitoring service, which has been reliable and responsive, in my experience. Their online technical support is worse than Wyze’s, though (and that’s saying something), and they don’t allow for permissioning/provisioning multiple app users, though customers have been requesting this for years, and they promised delivery this spring. Still waiting.