Admin to Create User type Foo that can then Create User type Bar I'm looking to build the following user structure in Drupal 8

Admin: They can create users of type Foo and Bar.

Foo: They can only create user type Bar.

Bar: They can only create content of a particular content type.

Is this achievable with any current module release? Here are some that I found that could help contribute to a solution:

I've seen profiles, but it has not got an official release yet.. and the feature set doesn't take care of my problem.

Rules, again not a full release but it can trigger events depending on a saved node/ submitted form etc.. 

Administer users by roles, sounds perfect, not tried and tested.. but noticed again the no official release.

Organic Groups. I don't need to entwine users and nodes (associating content with groups). Which is what I gathered when installing this module

The other option would be to create some custom code that is fired on the submission of a form to add a user via official drupal code... the only problem with this is making sure the code is correct and updated as new release of drupal is released for example. Would this be a good / stable approach?

Can anyone help point me in the direction of a solid solution? 

Thanks in advance.
@cwiggo Drupal doesn't really have a concept of a user 'type', just roles that a user can participate in, which I presume you know. You can of course layer 'types' on top of the provided structures using additional fields and tables. You've obviously looked at some of the candidates for helping with this, but have you considered Organic Groups, which might be closer?

As for using projects before stable release: my best suggestion is to dive in and help get a project over the line, perhaps by contacting the module maintainers and offering to help directly. There are however a lot of sites based on 'dev' modules; the maintainers just have to evaluate the code, the issue queue, and the overall risks/benefits and make a decision.