It's not a great workflow - I've found that using anything scripted ends up running into one of the various issues with print.
For example, if you render -> present in external web -> print, on my Chrome, it looks ugly as sin. It loses the slide sizing and formatting.
My current "this works ok" from Posit Workbench is to Render -> Print (this brings up a new tab) -> CTRL+P to bring up Chrome's print dialogue -> bypass Chrome, and print using system dialogue -> save as PDF. This avoids issues with Chrome's printing, and with the slide sizing, and seems to get close-to-visual-truth for the printed PDF vs. the RevealJS formatting. The Render -> Print stage in Posit Workbench brings up a continuous scrolling variant of the slides, which upon being printed recognizes the size and works ok.
I'd love to auto-render to PDF in a way that's good and keeps all my formatting, but I haven't found anything that's 100% (especially for footnotes and references and things - the CSS for those seems to 'fragile' somehow and breaks at the drop of a hat). And I always tweak slides slightly before each class, checking for typos and stuff, so I just print each one as I need it.