For a man that loves winning and competing as much as Magnus I find it difficult to imagine he wouldn't be playing if he felt himself a significant favorite. His last opponent is a character with a well deserved reputation for implosion. He was playing no less worse than Magnus for 6 games, in a 12 game match. He then lost a single hard fought game and did his thing, blowing up and losing 3 of the next 5 games with abysmal (by his standards) play. That
could happen again, but I think it unlikely and I'd say Magnus does as well. Nepo seems to have improved his mental game, and has been in great form as well - having just dominated a very strong field in the candidates with the highest score in modern times.
Carlsen is very strong, but his title defenses have never really reflected that - ironically with the most recent exception. In the two defenses prior, he only managed to draw the classical section and relied on tiebreaks. His defeat is all but inevitable, and I think he wanted to go out undefeated. I think the one opponent he was hoping to be able to play against was Alireza Firouzja. Alireza is young and will probably become a world champion contender at some point. But Magnus would have been able to count on Alireza collapsing under the unique pressures of a world championship match and let Magnus then go out on top having undefeated having defeated champions from 3 generations. Instead Alireza collapsed at the candidates, scoring less than 50% in spite of being the (at the time) 2nd highest rated player in the world.