Can my manager approve a refund from their own phone, or do they have to walk over to the counter?

They walk over, and that is deliberate. When a refund needs approval, a box appears on the cashier's device, the manager taps their own name and types their own four numbers, and the refund is recorded against the manager. The cashier stays signed in and carries on with the same screen. A manager can also be signed in on their own device at the same time for their own work. The Staff, PINs and hours tab in the docs explains how approval works.