Can I charge or change the SIM?

[TimothyN]

My understanding is that the supplied SIM has a very low data allowance. Can I replace it with a cheap Giff-Gaff or something so I can watch YouTube or whatever?

 

[mg4mc]

No, it's not a physical SIM, it is a multi-network eSIM. And I expect only their eSIMs can access the MG servers.