You can override vue js by override view file.
You can read this one - https://forums.bagisto.com/topic/221/how-to-override-view-file-in-bagisto
For overriding admin file:-
So you need to create a view file (In your package & follow same path structure as core 's view file consist ) & publish this file according to path of that suggested in above topic or core's view file has, in your package's service provider. Like
__DIR__ . '/../Resources/views/admin/catalog/products/edit.blade.php' => resource_path('views/vendor/admin/catalog/products/edit.blade.php'),