Looks like fragment is just an indirection with inlining. The closest built-in is maybe wrap here otherwise you could define your own. I don't think there is a need to change anything in Scriban to provide such support.

I started using HTMX lately and this great library for templating. It would be great to avoid having to split my HTML into tiny fragments in different files making it really hard to reason about. Fragments would be great!

You mention defining your own. How would I go about doing that? What would it look like in scriban to do something like mentioned here https://htmx.org/essays/template-fragments/?