How can I expose event creation fields on Drupal 8 front end without CiviCRM Entity?
If an extension isn't on the table, then I think that CiviCRM Entity is the way to go, despite the lack of a stable release.

For what it's worth, it's not terribly uncommon to have sites in production with modules that don't have stable releases.  It means more testing ensuring it works for your use case - but that testing also helps build toward the common solution that in a few months will be the standard way of doing what you're describing.

You may also research the Form Processor extension - but this relies on having a Drupal module like CiviMRF, which doesn't have a D8 version.

Finally - I would chat with the folks behind both of these solutions.  In particular, https://chat.civicrm.org has a "CiviCRM Entity" channel where you can talk with the authors.  They may also be open to a sponsorship to prioritize the features you need.