Does a separate package with the elasticsearch8 namespace have to be created and maintained here or should a meta package be set up? Unfortunately, elasticsearch8 is required as a dependency for existing packages in Debian that need to be updated, as well as for new dependent packages.
Do these two packages have a different API, but need to coexist? In that case, it's probably best to create separate packages with different names. Debian has many examples where this was done: python3-psycopg2 + python3-psycopg python3-boto + python3-boto3 libboost* clang-* I think it's also common to add the SOVERSION to the end of lib* packages.