I just noticed that EF says DONE4 base pricing ex-ALG is US$5962. Algeria is included in "Europe" for OWE purposes, and in addition to nonstops to/from LHR, Royal Air Maroc shows Algiers as a destination from CMN. I can't find any flight schedules for ALG-CMN on ITA, but maybe that's Covid-related. In "normal" times you can access quite a few international and intercontinental destinations from CMN. No idea about surcharges or nuisance fees that RAM might charge.