Sounds like you are trying to find a way to “build” your public assets – this is commonly achieved using Task Runners – Grunt or Gulp are two well-known examples.
Grunt is part of Node.JS, so you would need to download and install the node.js app and then find the packages you want to use – such as dart-sass for scss or uglify for minification of JS
The last step would be to config the gruntfile.js for your project or sub modules – how this works is very specific to you needs, but there are good examples available on the https://gruntjs.com/ website.
As far as structure and distribution of your plugins, as these probably do not sit on wordpress.org – you need to find a way that works well for you – we use public and private repos on github, which gives us versioning via Git, a good CI pipeline, and also a good way to allow multiple developers to work on the same code base.
We create a new repo for each plugin or theme.