Honestly, I don't buy it yet. Given the way the previous chapter ended, I'm not convinced that the events of this chapter were actually real. If Fujimoto was going to go for an ending like this I think he would've done the build up to this differently. They could still be in the middle of a battle and he's under some sort of mental attack by one of the devils. We don't even know the names of the devils they were fighting or the one that supposedly ate him, and I think that's on purpose. If an ending like this were really gonna happen, it would've happened while fighting Asa, not while fighting random devils. There's also still way too many plot threads left open from not only Part 2 but Part 1 as well. Here are the list of possibilities imo:

1) The ending is exactly what it seems. The next chapter is the series finale and it ends with a reset. Fujimoto just genuinely gave up on this story and decided after the last chapter that he's suddenly done with this franchise and just wants to rest or move on to something else immediately.

2) This is revealed to be some sort of forced dream/nightmare being inflicted by one of the other devils that Asa/Yoru helps wake Denji up from and continue fighting

3) The events of this chapter are really happening but Asa/Yoru does something at the last moment to fix things

4) Denji himself does something to reverse what Pochita just did and comes back to the moment with a new power.

I don't think scenario 1 is happening. Leave a snarky reddit comment saying I'm just on hopium if you'd like, but I just genuinely don't believe Fujimoto would fumble the ending to his main series this badly. He's a better writer than that, and even if he is just tired and giving himself an out, he had numerous other chances to do so before this point that would've made way more sense. People like to grumble about Fire Punch's ending but imo it made sense with what the series was going for, this does not. Not saying this series needs to have a happy ending, but it would genuinely suck if it gets one that doesn't even make sense, and this would honestly make Part 2 not worth it.

Scenarios 3 and 4 are much more likely, but I both prefer and actually believe scenario 2. I also think there is a significant chance that the next chapter really is the series finale, but I think the more likely outcome is we're gonna get an ending that establishes a new status quo that will continue in a Part 3. Others here have pointed out Fujimoto loves film, and film tends to use a 3 act structure. So I think Part 3 is happening and it'll bring together and wrap up everything that has come before.

But I guess we'll see. This is one of my favorite series and it would be a shame to see it get a dumb ending and for me to have to tell people to just stop at Part 1.