I doubt if it is fully implemented yet.
I do see in the signal flow chart that there is an input to the dynamics sidechain part, but have not found a way yet to adress it via any routing.
There seems no sidechain input drawn to the VST/AU section so that would be a good second question for if/when that will be possible.
Fairlight is still in the base state, where more advanced stuff like sidechaining , or editing / deleting automation data, or even more advanced audio editing besides a simpel razor, seem to not have yet made it to the first release.
For now stability trumps features so i am ok to wait a while . Its already a huge improvement over what we had before. And i must say i so far like fairlight even in its not full potential reached state. Just that fact that it eats all my vst/au stuff is a huge plus. And the possibility to easily create stems , sub mixes, different main mixes, different speaker setups that you can change with a simple dropdown, etc is also very cool stuff
I do sorely miss the possibility to create presets for all this stuff as it gets boring very fast to keep recreating the same settings every time for some standard compression/limiting stuff etc. But it surely will come....
edit: ah Peter just beat me