Salesforce CLI with Multiple Packages - Improve Scratch Org compatibility

[RemyVULTAGGIO]

The problem :
Following the best practices in Salesforce led me to have a multiple packages SFDX project.
The project is splitted in several packageDirectories (sfdx-project.json). Each Package Directory stands for a Feature of my Salesforce Org. Some are big, others are small, but every Package is standalone.
While naturally using a Scratch Org in developping phase, I encountered a painful constraint : sfdx force:source:status/push/pull commands include every sources of every Package Directories. Thereby I can't focus on a specific Package,

What I am trying to do :
In a multiple packages SFDX project, as a Developer, I want to be able to create a Scratch Org for a specified Package Directory, so that I can focus on a Feature.

The solution I would like :
As, in the "sfdx-project.json" File, every Package Directory can have a Scratch Org Definition File ("definitionFile"), I would suggest to use this information to limit the scope of synchronized sources between the Package Directory and the Scratch Org to the Package Directory Path ("path").
So, every time I create a Scratch Org using a "project-scratch-def.json" File, the Scratch Org creation process will scan the "sfdx-project.json" File and gather the corresponding "path"s in order to list the sources that can be synchronized.

Alternatives I have considered :
I thought of three more possibilities but put them aside as they divert best practices, cli commands and configuration files from their intended purpose :

• Add a new field (e.g. : "paths") in "project-scratch-def.json" to handle the synchronizable sources paths.
  {
  "orgName": ...,
  ...
  "paths": [
  "sfdx-source/feature_01", "sfdx-source/feature_11", "sfdx-source/feature_06"
  ],
  ...
  }

• Add a new parameter to the sfdx force:source:status/push/pull commands to handle the synchronizable sources paths.
  sfdx force:source:status --paths "sfdx-source/feature_01,sfdx-source/feature_11,sfdx-source/feature_06"

• Split my Features into seperate SFDX projects.

Additional context :
Just handle a single Path would be already great! ;)

I think this is, in a way, linked to the following issue : #379

I guess my feature request has already been identified by your team but, as far as my research led me, I did not find any issue allowing to clearly follow it.

[mshanemc]

The project deploy start command lets you specify one or more paths, with tracking enabled by default. So you can do with commands what this feature request would do via the project file.