I am working on a Rube Goldberg project that will turn on a Shelly dimmer on when motion is detected from a Shelly motion sensor and off when the motion stops.
The reason for this complexity is that the Shelly motion sensor uses MOTT to report changes of state. I have not used MOTT. I would prefer to beat my head against a wall to learn something that I can use.
The easiest way might be to create a virtual device, have a specific event on that device added as a trigger for your rule, then send the appropriate command to that device via Make API. Turning in a switch is an easy choice, though you'll probably also want to configure the "auto off" preference in that viruta switch so it's effectively momentary and ready to turn on again later.
Alternatively, you could leave MakerAPI out of this part entirely and just create a local or cloud endpoint trigger for the rule (these are trigger "capabilities" you can add like any other). Then, just do an HTTP GET on that URL, which will trigger the rule.
A little more detail:
The Shelly motion "talks" MQTT, so it can not talk directly to HE. This is why I am using the I/O Actions in the Shelly, to send the Maker API commands (on & off) to get the ball rolling.
I like your idea of using a local HTTP GET. Seems to be a lot cleaner. I am confused about which URL to point to.
Or you could use MQTT on hubitat. One driver for the motion sensor and one driver for the dimmer. Then use Motion Lighting app or RM or Simple Auto or Basic Auto. @kevin has the driver(s) you need or you can roll your own in Groovy - it's pretty simple.