The reference links aren't part of the AST. That's why they don't show up. But I think you know this!
I don't know of a simple way of achieving what you want to achieve.
However, the details of your references are in the AST where they are referenced. So with this input:
...you get this AST (reporting using pandoc-ext/logging):
(#) blocks Blocks[3] {
[1] Header {
attr: Attr {
attributes: AttributeList {}
classes: List {}
identifier: "referenzen"
}
content: Inlines[1] {
[1] Str "Referenzen"
}
level: 3
}
[2] Para {
content: Inlines[1] {
[1] Link {
attr: Attr {
attributes: AttributeList {}
classes: List {}
identifier: ""
}
content: Inlines[1] {
[1] Str "1"
}
target: "https://www.youtube.com/@johnwitulski18"
title: "John Witulski"
}
}
}
[3] BulletList {
content: List[3] {
[1] Blocks {}
[2] Blocks {}
[3] Blocks {}
}
}
}
...so you could write a lua filter to collect the info from the links and output it at the bottom.
But I can't help feeling that you'd then really just be implementing your own simple version of citeproc!
Using citations isn't too hard, but there are definitely more moving parts. I could provide a mock-up if that would be helpful.