They are Bluetooth Wireless headphones, so they should be able to pair just fine with an Apple Watch.
Have you put them in pairing mode per AKG's instructions?
See this link about using Bluetooth accessories with Apple Watch --> Use AirPods and other Bluetooth accessories with Apple Watch – Apple Support (UK)
Often the biggest reasons devices won't pair with something like an Apple Watch are:
- They are already paired to another device which is nearby and powered on
- The device being paired is not in pairing mode per the manufacturers pairing instructions