Actually, it's probably possible with Autohotkey and Extendscript: you rig an AHK to first run your jsx which saves a pdf and also maybe stores the name/filepath of it in a text file somewhere. Then you have you ahk script wait a while to see if your text file is updated and the PDF has finished saving- at which point it can trigger Outlook to run with pre-filled items and attachment of the pdf file you've just saved.
Here is the ahk email google link I've googled up: Outlook email, attachments, signatures (COM, HTML) - Scripts - AutoHotkey Community
I kinda wanna try doing this at my work too.