weanomic
Notification through their app ? (Or SMS, email)
Some apps require the Google Play Service to be installed on your device before they can be downloaded (use the "App store" application to do this)
If you've changed the permissions for system apps, it's better to reset them to their original settings.
One user reported having to use a QR code to install the eSIM. Google Play Services has been installed for his device.
However, Google Play Services should no longer be required on the main GrapheneOS profile to activate the eSIM.