Think about how more complex, uncommon, or otherwise edge-case-y Pipeline code could be useful in the Blue Ocean ATH.
The inclusion of complex, or even just uncommon, Pipeline code in the Blue Ocean ATH might help to avoid issues like JENKINS-47480. That particular issue includes samples which could be used to recreate the problem.
As users open issues, when we are lucky enough to have them provide sample pipeline code, we could store this code in a "Hall of Fame" repo, and utilize it in our automated testing.
This is a tricky balance to strike, because the more fancy one makes an automated test, the more fragile and hard to maintain it becomes.