https://www.cbr.com/doctor-who-john-boyega/

John Boyega pitches an idea to play a version of the Doctor in the BBC's Doctor Who, but only for one episode in a multiverse storyline.

John Boyega's Cameo Wish Reveals A Doctor Who Guest Star Problem (https://screenrant.com/doctor-who-guest-star-cameo-problem-john-boyega/)

John Boyega’s desire to play a one-off Doctor alongside Ncuti Gatwa reveals the big problem Doctor Who's universe faces with bringing in big stars.