I'm glad that Poppy is eating her "junk food", and that she seems to be feeling ok.
According to Willa's vet, her lifelong IBD had probably turned into intestinal lymphoma. Under this presumption ( she never had a biopsy done to prove that), her vet put her on the chemo drug Chlorambucil. It's not delivered by IV, but is an oral chemo drug, and it was compounded into a seafood flavored treat, which Willa gobbled right up.
Like you, I would have never done weekly IV drugs, she would not have tolerated that.
It resolved her diarrhea, and it gave her an additional 7 month of good quality life.