The jenkins core+plugin update yesterday evening ( DM-17945) included a new plugin, which appears to be in the early design stages, that adds a view of jenkins Executors
to Blue Ocean. Unfortunately, it only lists that an Executor (a slot for a build to run under an agent/node) is in use and does not indicate by which build. However, it does avoid the need to exit to the classic UI to get a sense of how “busy” the system is.