Other options:
GraphQL API (My personal favorite, and is stupid easy, if you’re on premise, install the Apollo GraphQL server with your on premise MongoDB cluster and you can route the Apollo GraphQL to the Atlas, unless Atlas GraphQL API is broken) Or if it’s Atlas to Atlas, GraphQL to GraphQL via building an API with it to just send and receive the data.
Atlas Functions HTTP service (Rest API)
There are a bunch of other options to do this, just listing a couple of more for you.