Bytecode support for Gremlin API is scheduled for public preview, December 2019.
Thanks.Dave Bechberger commented
The fluent API part fo this should already exists with the Gremlin Language Variant functionality that has been developed as part of the Tinkerpop standard. This has already been implemented in .NET in the Gremlin.NET driver. http://tinkerpop.apache.org/docs/current/reference/#gremlin-DotNet
Work for this feature has been started. Will update here when this feature becomes generally available.
Thank you both for your feedback on this. We will put this under review and revert with an update after our next planning cycle.