When an Android mobile device is locked to a network carrier, it will not allow an eSIM to be downloaded from a carrier other than the one it is locked to. If an attempt is made to download such an eSIM, the phone will show the message “You can add this eSIM, but you won’t be able to use it because your phone’s locked to a different service provider”.
Unfortunately third-party apps are not allowed to determine if an Android mobile device is locked to a network carrier. This is why it is important for you to ensure upfront that your Android mobile device is not locked to a network carrier before you purchase a GigSky data plan and download an eSIM.
In the case that your mobile device is locked to any of the US carriers, you can follow the steps given in the article below to have it unlocked: