There's 'Yuji and Nobara: Unseen Connections'. This fanfic delves deep into their friendship that could potentially turn into something more. It has some really interesting scenarios where they rely on each other's strengths and learn from their weaknesses.
Itadori did indeed die in the manga. His death had a significant impact on the story and the other characters. It was a turning point that led to many new developments in the plot.
Itadori is quite powerful in the manga. His strength lies not only in his physical abilities but also in his determination and the unique powers he acquires along the way. He's able to face off against formidable opponents and come out on top more often than not.