My first thought- have a Granadan or mudejar refugee simply use their identity as andalusians/ personal political skills to form a base that allows them to challenge the Saadi rise and supplant the wattasids.
My second thought- thats difficult because the rise of the Saadians and later the alaouites was as much a religious affair as a political one, given how strongly Sufi saintly auras legitimised Muslim monarchs in the early modern era and the Granadans simply don’t have those Sufi connections. Also the mudejars are at a double disadvantage here because of the fact that they were otl seen as second class Muslims by both granadans and Maghrebis (a mudejar shouldn’t be allowed to lead prayer, their testimony is worth less in court etc) because they’ve been forced to adapt to being Muslim in a situation where knowledge of Arabic and access to Islamic authorities is severely limited, leading to a culture of translating into Aljamiado. Because the Quran, hadiths and other materials for the religious sciences were now in the exact same language that they natively spoke, that also meant they were less reliant on fuqaha to interpret them and pronounce rulings.
My third thought- it would make for an incredible story if an incredibly talented mudejar refugee in the Maghreb recognises how his understanding of Islamic culture differs from standard Maghrebi culture and instead of assimilating, vigorously defends it and becomes a religious reformer- insisting on the idea that the ummah should be able to understand the religious sciences in their own vernacular and that there is no real need for fuqaha at all, as all good Muslims should have enough training in the religious sciences that consensus can be found. He calls for a return to the first days of Islam, where the caliph ruled with the assent of the shura and consulted them- but also is inspired by his practical first hand knowledge of the Cortes of Aragon as a check on monarchical authority.
He pronounces himself the mujadid of the second Islamic millennium, come to dispense a new age, just like Safavid shahs and Mughal emperors were doing at the same time in the east, and his religious fervor and political innovations attract allies. After seizing a few major cities, he builds on his calls for the democratisation of the Islamic sciences by establishing an Arabic type printing press which he uses as an effective propaganda machine to further disseminate his reformist agenda. Also maybe as a young man he personally served in the Aragonese army during the conquest of Granada, as many mudejars did, and that gave him first hand experience of proto tercios- he’s thus able to back up his revolutionary credentials with cold hard victories, and the first step of his movement was to secure access to firearms.
By the 1600s, the Maghreb has a new caliphate- one with a self consciously mudejar identity, with a form of Iberian romance in Arabic script both the first language of the reigning dynasty and prized as a language of culture, maybe even the primary administrative language in some regions- this slowly seeps through maghrebi society such that andalusi, arabi and Berber are the three maghrebi languages. Given enough millennial fervour as we approach a thousand years of Islam, this movement could potentially seize the entire Maghreb- at which point the Iberian kingdoms should be very worried. Given the financial crises of Philip IIIs reign who knows- the Mudejar caliphate might even set its sights on a capital in Seville.
This process might take a couple generations- the first would be needed to establish the movement as a religious reform that wasn’t going away, the second to catapult that reform movement into political power, and the third to begin enforcing that over the political class of the whole area. Refugees from Spain who were otl bilingual in Arabic and romance who otl would have dropped the romance for Arabic here maintain their knowledge of romance to signal political affiliation with the rising star of the new caliphate.
