Creating a ticket system with core only. How to modify fields on full_content view without reloading?
Another approach would be to use a form mode instead of a view mode. Put there the fields you want to make writable and add the read-only information in a form alter hook (or separate view block if you want a UI only solution).

To use the form mode you need a module like Form Mode Control or some custom code,  see this good tutorial https://www.webomelette.com/render-custom-entity-form-modes-programatically-drupal-8.

While quickedit is a single purpose solution for in-place editing of web content, you can now that you have a real form do all kind of tricks to get the behavior you want, for example implement autosave: https://www.urbaninsight.com/2016/08/21/how-implement-ajax-autosave-drupal-8-forms