Do you have any good sources of reading for the eSIM standard with regards to this? Projects like Ukama make it look easy to issue your own eSIMs but I don't u

Do you have any good sources of reading for the eSIM standard with regards to this? Projects like Ukama make it look easy to issue your own eSIMs but I don't understand whether it's something they provide as a service to their users through a central authority or if it's actually a proper roll-your-own system.