Issues with Using =DUST() Function in Google Sheets Script

I'm playing around with the Google Sheet script (https://docs.dust.tt/docs/beta-google-spreadsheets). It works great if I use the Call An Assistant UI. But I'm not able to use the =DUST() function as shown in Alban's video. And looking at the script code, I don't see such function. Maybe it was a thing, but got removed?