+1 to this comment. My team is heading down a similar path. Theres a single, defined and versioned, external API. Internally there are a handful of “microservices.” All have their own APIs, models, versions, etc. Some are invoked over remote HTTP, some are a function call, some have their own endpoint and several microservices behind it, some are bundled in to the same binary. In each case the caller and the receiver doesnt know (or care) about the implementation. The important parts are the service boundaries and definitions. Not the packaging.