These morphed from my previous MQTT + Zigbee combo drivers, but @dandanache's newer IKEA Zigbee Drivers are better, so for any directly-connected IKEA devices I use those instead! 
As with some of my other drivers, I've mothballed the old ones to concentrate on these MQTT-only versions.
Installation
You will need the Zigbee2MQTT Routing Driver installed first.
Once you're up and running with that, make your life easy and search on Hubitat Package Manager for "ikea" and you should see IKEA Drivers via Zigbee2MQTT from BirdsLikeWires.
Otherwise, you can get them straight from the BirdsLikeWires GitHub if you like to do things manually.
- BirdsLikeWires Library Bundle - Bundle URL: ZIP
- IKEA Symfonisk Sound Controller - Import URL: RAW
- IKEA Tradfri Button Driver - Import URL: RAW
Once the driver you require is installed, you'll need to tell the device created by Zigbee2MQTT Routing to use it, otherwise it'll just sit there being a generic "Zigbee2MQTT Device". Click on the arrow next to "Zigbee2MQTT" in your Devices list to show the child devices, then click on an IKEA device you'd like to use one of these drivers with.
Go to the Device Info tab and change the Type to the matching driver, down at the bottom of the list in the User section.
Click Save, then hop back over to the Commands tab and press Configure to set everything up. If you forget to do this it'll sort itself out as soon as the next message is received, so don't fret if you forget.
Enjoy!
