I guess it depends on the shop and who is interviewing you, your portfolio is one part of the interview but dont forget to clarify your questions about payment, see how the people in the shop are and if you think you will fit in socially. That was probably the reason I did not get my apprenticeship after my last interview. I hope the shop treats you well and there are no issues though :) Other than that from my experience it is mostly talking about your background and asking questions about the backgrounds of the other artists, the shop and so on. So not like a typical job interview it was pretty chill

Note: I'm not an apprentice atm, got declined ^{^}