I have gone through the requirements you mentioned it looks similar to what I am currently working into projects so I would be happy to work with you to answer your questions and give you some practical experience on microservices development.
I hold good exposure on spring boot, spring gateways, docker, Kafka , spark, etl, service bus, service registry, 12 factors principal of microservices, no SQL, mongo db, Cassandra, hbase, CI/CD
let's connect if you are interested