Just to be clear there is only one pipeline?
I want to get the most out of GL and I find the documents imply that there are multiple pipelines confusing.
Pipelines — Graylog 4.0.0 documentation
For example, if there was a second pipeline declared with a stage assigned priority 0, that stage’s rules would run before either of the ones from the example (priorities 1 and 2, respectively). Note that the order in which stages are declared is irrelevant, since they are sorted according to their priority.