Earlier quoted context omitted.
Yes, I should have been more specific that collagen gets broken down into collagen peptides. I didn't think I needed to be that specific since it's like the difference between Calorie and calorie (i.e., the distinction is not relevant to the discussion on hand). We know that the body can use collagen without digesting it first because collagen masks are used to heal burn victims. See, for example: https://www.ncbi.nl…
Maybe I wasn't specific enough here. When I said "smaller peptides," I should have instead written "free amino acids, dipeptides and tripeptides." The two papers you cited refer to topical application, but your statement in your first comment said that it is easier to get collagen from dietary sources. What I'm asking for is what size of peptide you're calling a "collagen peptide" and a source supporting a mechanism…
See https://academic.oup.com/fqs/article/1/1/29/4791729 for a discussion of bioactive peptides.