So I've been thinking, could the ending be the beginning, and viceversa?

  
I don't really have much proof because I suck at researching and theory crafting, but please hear me out.

  
We know at the end of C1 we can roam around hometown and talk to "old friends", but they don't seem to acknowledge the events of Undertale. It may be a nod to, well, Undertale, but it can also mean something else. This could be not the first time Kris talks to them.

When we die in Deltarune, we hear Gaster talking to us, just like at the beginning of the game. We also know that the last panel of the prophecy is a tragedy. We don't really know \*what\* happens, but it might have something to do with Kris's hand.

What if the "bad" ending (no eggs, no shadow crystals, no weird route) has Kris dying/sacrificing themselves, to the extent that a simple "time warp" to the last save point isn't enough (maybe even getting lost in the game's code? might be completely unrelated tho...), so the only option to have a chance of changing the prophecy to a better ending is to start from scratch on C1.

Also, in Undertale there are a few mentions of timelines starting and stopping (mainly from Sans), so what if they also have an impact on Deltarune?

  
As I said, I suck at making theories, and this is mostly a shower thought per se. Don't take this too seriously, but if you think I might be onto something please help me expand on this.

Time loop theory?