Hi mate,
I think aside from the general pilot competencies out there, it’ll probably be a lot more about how flexible you are (being called last minute to operate) and how you can go do that extra for the customer (who are presumably gonna be very upmarket). So find examples for those I’d say and have those prepared alongside the usual questions you can get at an airline interview. Operational knowledge could come up in a tech test of interview and flying technique I suppose through a sim assessment?
Good luck.