Elgato Avea bulbs do not support Elgato Eve, HomeKit, or Siri.
HomeKit and Eve are Not Supported
Elgato Avea was designed and released before HomeKit products were made available.
All Elgato Eve accessories, and other HomeKit-compatible devices, need special internal hardware that provides encryption and other functionality. Elgato Avea does not have this special hardware.
Therefore, Elgato Avea bulbs currently in circulation cannot act as HomeKit accessories, or work with the Eve app.
Siri is Not Supported
For Siri connectivity, Elgato Avea bulbs would need to be HomeKit accessories. Since they are not, you cannot use Siri to directly control Elgato Avea bulbs
Elgato Avea and Eve Energy
In countries that support Eve Energy, you can use Elgato Avea bulbs with HomeKit, Eve and Siri indirectly.
1) Connect your Elgato Avea bulb to a lamp
2) Connect that lamp to Eve Energy
3) Use Elgato Eve to tell Eve Energy to switch on or off, and that will turn the Elgato Avea bulb on or off.
However, to actually control the color and other characteristics of your Elgato Avea bulb, you would have to use the Elgato Avea app on your mobile device.