Publish dynamic pages?
I'm not sure if in D8 webform submissions are useable, fieldable entities yet.

Although I believe the EForm module may work as you expect. Allowing you to define forms the public can fill out and then very easily turn the content into drupal "pages" or reachable content at some url pathauto pattern.

Allowing the public and administrators to modified different fields, or subsequently edit submitted data is a Roles/Permission issue that drupal Core or other modules such as Field Permissions will let you achieve.