@jochemr That "Flic App" plugin in Homey is not an official one by us. It appears to simply set up a web hook which can then be triggered as a normal http request.
We already have our own Homey integration directly inside the Flic app which is able to execute scenes/flows in a Homey, by authenticating the Homey user inside the Flic app.
If you have a Flic hub, then clicking the button will still work if the person with the phone leaves the house.
Currently, there is no good way to connect a Flic button directly to the Homey device. We did some attempts some time ago together with Homey but their Bluetooth stack was not good enough to handle triggering devices.