Hey @jordanbrooks — thanks for the ping on this, it seems like this is still not yet supported in Retool but I will bump this feature request internally and update this thread as soon as a feature is added
I am also running into this problem - I've been to Google Support and they advise that it's an issue (as Pierre says above) of the Oauth scope being added per this support article
BTW I found a workaround that worked for me, so I thought I would share here. In BQ, you can set up a scheduled query that outputs to a BQ table. For the BQ table that I wanted to use in Retool, which I couldn't use before because it's linked to a Google Sheet, I just created another table that serves as an extract of the original sheet, and I have a scheduled query that updates it from the Google sheet once a day (though you can schedule it to be more frequent if you want). I'm able to access the extracted sheet via Retool.