69 votesJames commented
Sure, do you already have Harmony Hub set up with Home Assistant? If so, then there will be a file in your config directory called "harmony_REMOTENAME.conf". It contains names and ID numbers for all of the activities and devices you have set up, and commands for each device. You can directly send single commands to these devices using the remote.send_command service. Docs with an example here: https://www.home-assistant.io/components/remote.harmony/James commented
I also gave up waiting and just ended up using Logitech Harmony. You can use HomeAssistant to fire specific IR commands to a room triggered by IFTTT etc.