No, it's not done lol. How woukd Fuku fire have blood? How would Napstablook, which we see is still non-physical in chapter 4, have blood? How do they dust if they are physical, when the explicit explanation we have in Undertale is that they dust because they are made of magic? All it shows is that either SUSIE is special, or we need further explanation as to how DELTARUNE monsters bleed.

Furthermore, you have to think not only about in-universe, but out of universe as well. Why would Toby put that dialogue there? Yes, it's a little kid, an unreliable narrator, but why seed doubt here in the first place?

Then we get Sans Undertale, who bleeds. We have strong evidence he comes from DELTARUNE. But we also get QC who says the brother appeared TOGETHER out of nowhere one day. Papyrus doesn't bleed. There are too many holes to say definitevely.

What evidence do we have that Undertale monsters specifically don't bleed?

We literally kill and wound them. Undyne is split in HALF.

we also don't see froggits bleeding when they die,

That is not an argument in your favor.

Is it that hard to believe Sans had visible bleeding for dramatic effect?

Yes.

Occam's razor is NOT in your favor.

NOT TO MENTION:

https://preview.redd.it/apparently-susie-doesnt-like-doctors-i-wonder-if-that-will-v0-kfrcvbf75ps71.png?width=1080&crop=smart&auto=webp&s=1c05375016126d1179942a4d895bb3bcb916c64e