Open the project file and run the bottom node Import image (red arrow 1). Chose the Cache intermediate results option to see the outcome from all nodes.
Observe the cache (red arrow 2) and notice that the image has multiple channels (red arrow 3). In order to split the channels, search for a suitable node (red arrow 4) with the keyword split (red arrow 5). Choose the Split channels node (red arrow 6) and add it to the pipeline (red arrow 7).
The Split channels node behaves exactly as its equivalent from ImageJ (channel splitter).