~~Not only is it not an option in smidge, the Umbraco JS loading APIs in the back office don't support it either (I've got an open bug somewhere that can never be fixed)
There is a (horrible) workaround.
Build the script tag dynamically in "regular" JS and add it to the DOM, like this:
https://github.com/JasonElkin/maximum-markdown/blob/main/src%2FMaximumMarkdown.Backoffice%2Fwwwroot%2Fdev-bootstrapper.js
You can ignore the check I do to see if it already exists, it isn't strictly necessary.~~
Sorry, for some reason I assumed this was for the backoffice. Ignore what I said. Just use a regular script tag.