Autor here. Generally I feel much more confident about external services 'pulling' the status. But I have something cooking up to reduce the friction of external calls and possible process blocking...
Browsing StackOverflow I saw a suggestion to use NOTIFY/LISTEN for stuff like this (it was a question about sending emails from postgres) – an external process listens for notifications and runs the external commands. No blocking risk, and the external process can run on a different host, but you have one extra moving part to look after.