Most trips start in Algiers. The capital and its airport, Houari Boumediene, sit on the Mediterranean coast, and this is where Mobilis coverage is at its best. You get steady 4G in the city center, around the Casbah, the Martyrs Memorial, and out toward the beaches at Sidi Fredj and Tipaza.
Set the eSIM up before you fly. When you land, switch on data roaming for the travel line and you are online before you reach passport control. For a few days of maps, messaging, and the odd photo upload, the 1 GB for 7 days plan at $1.57 is plenty. If you plan to stream or share a lot, step up to the 3 GB for 15 days plan at $3.64.