iPhone + Homekit = extremely good presence.
It's not an easy thing to build out, but it seems very reliable to me.
You create 2 Homekit Automations (one for arrive, one for depart,) and they update Hubitat virtual devices. That part is apple easy, the hurdle is to enable automations by having a Homekit hub. AppleTV, HomePod, (always on) iPad.
Next comes Homebridge and a RaspberryPI, Apple Computer or a Linux box can be used. So lots of options to get Homebridge running.
In my case, (the most recent time) I got it started using an iPad that is always on and that worked great, as expected. Then I transferred the Homekit hub to an AppleTV. That worked and still is.
Homebridge is running on my Mac Mini Media Server along with everything else I can get on there. (DNS, DHCP, Web, etc.)
The iPhone's Home App, via Location Services, signals the Homekit hub, which runs the automation that informs Homebridge to set (or reset) the virtual on Hubitat.
Homebridge is really just a Node.js based app, so it works on anything that does node.js, I imagine.