Send check_mk notifications via signal-cli (requires https://github.com/AsamK/signal-cli)
Store script at /omd/sites/<YOUR-SITE>/share/check_mk/notifications
Adjust <SIGNAL-CLI-PATH>, <USER-SENDER>, and <USER-RECEIVER>
Integrate at WATO / Notifications, select Notification Method "Send via Signal"
Messages will look like: <HOSTNAME>: <NEW-HOSTSTATE> after <OLD-HOSTSTATE> (<OLD-STATE-DURATION>) at <LONG-DATE-TIME>
signal.py is an alternative implementation that uses Python instead of bash and requires that signal-cli is available on the system DBus Rename to "signal" and use instead of the original signal (bash) file