Yes, you can do that.
The editability is a setting of a data view ("Editable = Yes / No"). So your main page can have a data view with Editable = No, but your popup page can have a data view with Editable = Yes.
If you did not change this setting, but can still not edit the object in the popup, your user likely has no rights to write the attributes of this object. If so, go to your domain model, click on the entity and edit the read / write rights in the "Access rules" tab.