@Mariano Saenz (NS Eng Lead) does that version has any impact for anything except my own housekeeping?

In 19.1 you'll be able to run Installation Scripts as part of the deployment of your SuiteApp, and the input parameters to the script will be the version of the project as well as the version already installed in the account. Using that information you can then decide what logic to execute on your installation script(s).

But it is still gonna be independent of Bundle installations and bundle install scripts correct?

Yes. Bundle Installation scripts are only for bundles. This will be a new script type specific to SDF.