Ok well, here comes a big explanation.
So I don’t know about the deltarune part, but I do know that that comes from earthbound as an Easter egg. Why an Easter egg? Because some of the developers of undertale also helped make earthbound. However some people think that sans is ness From earthbound because of his diolauge and that note, but I think they’re just eggs. But back to the question. No, I don’t believe so.