You should be able to use `htmltools::htmlDependency()`
Like if I was trying to recreate `knitr::knit_meta_add(list(rmarkdown::html_dependency_font_awesome()))`, I could by:
```r
metadata <- list(htmltools::htmlDependency(
name ="font-awesome",
version = "6.4.2",
src = list("fontawesome"),
stylesheet = c("css/all.min.css", "css/v4-shims.min.css"),
package = "fontawesome",
all_files = TRUE))
knitr::knit_meta_add(metadata)
https://stackoverflow.com/questions/78659964/add-code-to-html-header-in-quarto-without-modifying-the-preamble/78660732#78660732