So this is a quick scenario we could imagine:
>No world wars leave tensions higher in colonial Africa. It becomes a reality that invasion could happen, and as such the 1910s and 1920s see small military forces of native africans be created, which would create an african urban proto middle class by the 1930s.
>No world wars allows for no great depression, and with more inventors and capital around, technology progresses faster. We see oil become more dominant early on, in the 1930s, and air conditioning becomes readily available in the 30s instead of 60s. This allows for limited urbanisation in several countries and faster spread of ideas. The truth is only a few people in colonised countries truly fought for independence, and as such we would only need small numbers in this Africa,
>Earlier spread of TV into households 20 years earlier without the WWs. A big reason for opposition to Vietnam was that the horrors of the war by 1970 were broadcasted straght into people's front rooms. This would happen by 1940 in our world, hopefully in colour too, so that the horrors of colonialism, victims of the Congo Horros, those living under segregation could be easily seen etc, so that opinion in the west turns against colonialism.
>Have widespread peaceful protests in the colonies. These could of course turn into riots, but by the 1940s we may see large urban areas, with a strong middle class advocating for independence and helping whip up the poorer people.
>Faster decolonisation. So even with all of that we may only bring decolonisation forward by a decade, so that Ghana for example would become independent in 1947 not 57. However I do think it's reasonable that by 1955 we could see all of the british colonies gain independence, followed by the Congo, some french colonies are gone.
>Good examples and foreign powers. For example in this world we could very well see an Egypt with Sudan being a great power in north and east africa, funding independence campaigns etcera. For example people in the UK drinking tea in their front rooms may be watching a crowd of tens of thousands demonstrate for independence in Nairobi, and they will probably have the attitude of 'these people just want to be free, why would we start shooting at these crowds for that' and politicans may be hard pressed. Shooting at them would almost certainly be seen as unpopular and probably a waste of money.
With all of this, all of Africa should be independent by 1970 at the very latest, and mostly by 1960, as compared to 1975 and 1980 IOTL.