I think breast milk jewellery is quite sweet actually, I have some EBM in the freezer that is coming up on a year and can't be used for my DD since it's from before we were dairy free, I had toyed with the idea getting something made. The website I was looking at was a different one, didn't have any umbilical stump products.
I don't think the milk jewellery is disgusting, it's made into resin so it's not like you have actual milk sloshing around gping rank!
The umbilical stump thing isn't really my bag, but I agree that it's not so different from curls of hair or ashes. I'm a nurse and we are often asked by patients if they can keep removed staples, teeth, metal work or appendices (teeth, yes; appendix no!).