I would love to hear the answer! I got my Flic Hub a couple a days ago, but I am a bit disappointed about the missing HomeKit support. It has been announced for over a year by now.
One of my use case for the Flic Button is to toggle my espresso machine on/off. It is attached to an Eve Energy socket. For now I have to ask Siri or open the Home/Eve app to power on/off, also when I am standing right in front of the machine.
Hope the HomeKit support is coming soon.