I realize now that I'm using quarto-hub for myself that it would be very handy to have something like a {{< now >}} shortcode in a document, then select it, choose a command like "evaluate", and have that shortcode become 2026-03-20 05:00PM EDT. That is, "send this snippet through a qmd -> qmd quarto render".

It's possible that I'm the only person who wants this, but I can imagine having lots of handy Lua filters in the project lying around and using them for this kind of use case.