How to submit multiple Flink Jobs using Single Flink Application

Several points:

Application mode, introduced in Flink 1.11, allows a single main() method to submit multiple jobs, but there's no mechanism for direct communication between these jobs. Flink's approach to fault tolerance via snapshotting doesn't extend to managing state in more than one job.

You could, hypothetically, connect the jobs with a socket sink and socket source. But you'll give up fault tolerance if you do this.

You can achieve something similar to what you've asked for by configuring a slot sharing group that forces the final stage(s) of the pipeline into their own slot(s). However, this is almost certainly a bad idea, as it will force ser/de that might otherwise be unnecessary, and also result in poorer resource utilization. But it will separate those pipeline stages into another JVM.

If the goal is to have separately deployable and independently scalable components, you can get that by using remote functions with the Stateful Functions API.

To maximize performance (and minimize garbage collection) with the sort of ETL job you've shown, you're probably better off if you take advantage of operator chaining and object reuse, and keep everything in a single job.