In case you stumble upon this thread, this is how I’ve managed it.
The error in your vue app regarding the angular/core can be resolved by using the proper import
import { WifiWizard2 } from '@awesome-cordova-plugins/wifi-wizard-2';
instead of
import { WifiWizard2 } from '@awesome-cordova-plugins/wifi-wizard-2/ngx';
I had to install an extra dependency called es6-promise-plugin via npm (here).
And that’s it, the wifiWizard2 can now be used without any errors, simple as pie ¯_(ツ)_/¯