How to create a field that references a Views Block display in D8?
Things are confusing because that's how entity reference works. All those things are entities, so they are technically referencable. As you found, block are actual block placements, which is not what you want. And view doesn't allow to select the display, so for your case, that's also not what you want. Drupal 8 core simply can't do that without custom code or a module (yet).

You either need a contrib module like Viewfield, but that doesn't have an official 8.x release yet. The blue box points to the contrib tracker issue, which in turn points to https://www.drupal.org/node/2220929, which has a link to a github repository where someone did an initial port. If and how well that is working already, I can't say.

An approach that would require a bit of custom code would be to have a list field with a few options ( since you don't want to allow all views anyway..), and based on that, there needs to be a bit of code that loads and calls the view and displays the results.