Is is possible to have an embedded sign-on/consent?

Theoretically, it is possible to enable sign-on/consent, but it is not recommended from the user security's perspective. 

If the sign-on is embedded on a website, then there is nothing that prevents the website from snatching the credentials. It is recommended that the sign-on flow is always opened in a new tab with a URL that you trust. In other words, MobilePay recommends the user to refrain from entering their credentials in an embedded web view, and always make sure that you enter a URL, that is separate, and that belongs to a website, that has your credentials (MobilePay in this case. 

For the same reson, MobilePay doesn't have experience with implementing an embedded sign-on, so we cannot help with it.