The other article looks interesting, though it too has "blue banana" errors. Laurent Schwartz's autobiography "A Mathematician Grapples With His Century" has a more believable account of Schwartz and Dieudonné's work with Grothendieck. The Grothendieck Circle website (https://webusers.imj-prg.fr/~leila.schneps/mitanni/grothendi... since they haven't done a good job renewing domains) has a lot of Grothendieck's own writings (mostly in French) and Wilfried Scharlau's biography (in German). I tried to read those some years back but my language skills weren't up to it. Machine translation is much better now than it was then, so I might try the lazy approach.

There is an incredible (alas unfinished) multipart Grothendieck biography by the German mathematician Winfried Scharlau: Wer ist Alexander Grothendieck? Anarchie, Mathematik, Spiritualität, Einsamkeit. I think an English translation exists, at least for the first and in my opinion most interesting volume: Anarchy. It mostly deals with Grothendieck’s childhood and his parents, who lived unbelievably fascinating lives as anarchists in pre-war Berlin.