Perhaps some kind of WMIT African socialism? Some afrobeutelism or african eduism?Which would definitely cause rebellion, especially with Zanzibar being used to autonomy and self rule. I can’t see Illuminism taking root because of the anti religious core parts of it (they’d be happy to kick out the Catholics but wouldn’t want to destroy Islam), and unlike Ethiopia they aren’t even nominally Christian so I can’t see a scenario where they become fascist. Perhaps Zanzibar is the nation where a form of Beutelism finally finds success.
Overall, there's plenty of stuff from 20th century black Africa that WMIT could take inspiration from.