I had lost form data on a website (Chrome/macOS), and was unable to follow the recommended resolution for Linux/Mac due to SIP being enabled (relevant comment). However, the associated page/tab was still open.
Through a bit of debugging, I was able to recover the lost data. I'll post my steps as a possible answer (but won't mark as accepted unless there's no better alternative).
My question: is there a better/easier way to get at that lost data? (without requiring a time machine to go back and install a browser add-on / disable SIP prior to the event?)