It wasn't quick, but it did seem to work. Here's the timeline:
- May 2018: I contact Google about being unable to export my accounting data from last month
- November 2018: after nothing but "thank you for your patience" emails, I complain to the AG
- early February 2019: I get a letter in the mail from the AG saying they'd forwarded the complaint to Google
- late February 2019: Google finally gives me my data [edit: I'd had April originally, but that was a separate request].