Custom entities in drupal 8

I am an avid user of d7, and am just getting into D8 development for work. The project we are currently working on involves creating about 3 different custom entities (not nodes, users, etc). I am not sure why, but D8 documentation is very sparse compared to d7 documentation, and there doesn’t appear to be a clear answer on how to create a custom entity, attach fields to it, and then create bundles of that entity with additional fields per bundle.

I have tried using drupal consoles generate:entity:content, generate:entity:config and generate:entity:bundle, but none of them seem to do what I am trying to do.

I am trying to specify a new custom entity type, and expose it to the drupal UI so I can define the fields for the base entity, as well as the fields attached to each entity type, similar to how nodes can be accessed using Structure > Content Types > Article/Basic Page.

In d7, you used to be able to use entity construction toolkit, but since that’s not available in d8 anymore, and the documentation doesn’t give a straight answer, I am stuck trying to figure out how to do it on my own.

Does drupal console just not support a way to create a custom entity, attach fields to it, and define bundles of that entity with their own additional fields?

If I have to go into the scaffolding and manually make changes in code to do some of the stuff, that’s fine, but is there a resource somewhere that explains to me how to do that? Because I haven’t been able to find it in the d8 documentation.