TL;DR: Added support for SYMFONISK Gen2 remote 
. Tested with modern firmware versions only. Watch out for the default repeating Held behaviour, the driver lets you suppress repetitions too and adds multiple tap support!
May take a few hours to auto-update! Check in the driver description that it mentions SYMFONISK before trying to pair it, if it was a Zigbee Thing just delete it.
Welcome to the Zigbee Buttons jungle
Three weeks ago I had no idea about how drivers or Zigbee buttons worked. Now, after RODRET, SOMRIG and STYRBAR I see it is a jungle because they are not really buttons 
. Sometimes they are on/off switches, sometimes scene selectors, sometimes dimmers, sometimes proprietary things. Sometimes all at once: that’s SYMFONISK.
Drivers translate all those different behaviours to common actions like pushed, held or double. That’s why adding support for a different model is far from just adding a fingerprint, usually you need a brand new “translator”, technically known as a message handler, especially with IKEA stuff.
The SYMFONISK gen2 remote
I’ve purchased a SYMFONISK gen2 remote to play with. Box says 2336 and comes with the modern 1.0.35 firmware where things work differently to the older ones (the jungle again 
).
It’s a Frankenstein! 
- Buttons + / - are meant to be a volume control for Sonos and behave like a dimmer, they even generate multiple Held actions per second if you keep the button pressed. Funny thing: for other models I added an auto-fire feature to automatically repeat the Held and here I added the opposite feature to suppress the repetitions!
Otherwise I couldn’t use it to toggle lights on Held, it would toggle multiple times. - Play / Prev / Next don’t support held, only pushed
. Boring! The driver adds an optional double-tap up to a useless but pretentious sextuple-tap 
. - Dots use custom clusters, like the SOMRIG, they support pushed, held and double-tap. Even clusters are different in old and new firmwares. The driver tries to account for both albeit only tested in the new one.
The custom features
Have the old firmware?
I’ve only tested the driver in my unit with modern firmware. If you have old versions, either update the firmware or test it and see what works. The button is already documented thanks to other communities so I accounted for old versions too but could not test it. I expect most buttons to work, the breaking changes between old and new are the dots.
Credits
The handler and the custom features are all original work but would not exist without existing knowledge. I found this zigbee2mqtt device info, this hubitat driver and this zigpy discussion with logs comparing both firmware versions extremely helpful to navigate the messaging-maze.