Yes! Flair is an official Honeywell integration partner. Flair integrates with all Honeywell WiFi connected smart thermostat models and room sensors.
Honeywell room sensors can be used as temperature sensors in a Flair System. At least one Puck is necessary to act as a Gateway to bridge Smart Vents to the internet. See How many Pucks do I need for my central system?
Have a converted garage, porch or extra room with a mini split, window AC or portable installed? Use Flair's Mirror Mode to have the room follow your ecobee set point, home/away and schedule.