I always wonder, when I see these threads, why no one ever wants to wonder how the French could have improved relations with the Muslim Algerian native majority to the point that the latter would themselves see themselves as French, in the sense of belonging within a greater France, and France thus winds up retaining Algeria integrally. With a loyal Muslim majority, fully enfranchised as normal citizens, participating equally in French society.
That too would surely require a POD in the 19th century of course. But so does white supremacy, unless one envisions a world where overt racism prevails generally.
I think I have a handle on why this rainbow France option of mine never got any traction, but it seems a shame, in contradiction to the best aspects of France's revolutionary heritage.
Of course the problem is that the whole French presence in North Africa was of course, like all colonial ventures, mainly at the expense of the natives, so reforming things to the point where they decisively buy in is pretty contradictory to the French being there in the first place. But if any European nation could conceivably pull it off, I'd bet on the French first.
When I consider how it might have gone, the first steps are very vague and perhaps hopelessly improbable, but if a halfway ambiguous improvement had happened already by 1940, WWII (assuming it isn't butterflied away) seems like a good tipping point. If France falls as OTL, but Algerian natives are at least somewhat enfranchised, then I think Algeria would not submit to Vichy. It would be the nucleus of Free France instead; by the end of the war the prestige of Algerians in general would be very high in France and postwar the unification and equalization would go smoothly.
In such a sketchy scenario, I figure the Algerians would already have impressed many if not all French people with their loyal help in WWI.
As things were OTL, the white-supremacist settlers of Algeria were the most inclined of French colonists, right alongside the colonialists of Indochina, to support Vichy and collaborate with the Axis.
It sure would be nice to have an AH where that was reversed!