wordpress plugin development across multiple websites published to elastic beanstalk

I have some plugins in development shared across multiple websites.

The websites are published to AWS EB using eb deploy (using git).

I'm trying to find a better development workflow and stopping to copy&paste plugins between the projects folders... but no success yet!

I tried using submodules, subtrees and composer but nothing gives me the flexibility to work on the plugin from the different websites and keeping all the code inside the root folder for the EB git requirements, while keeping git history for the plugin development cicle.

In fact, Elastic Beanstalk requires to deploy the whole solution through git, that means all the needed source files has to be committed in order to be deployed. For example, when the plugin is loaded through a composer git package is not going to be pushed into the main git repo and then is not going to be pushed to the server.

Any suggestion is really welcome.