Thanks for suggestion. I have tried to follow the instruction here https://developers.google.com/apps-script/add-ons/publish to publish SheetSQL as an add-on, but I was stuck at step 4, since I did not see "Deploy as Sheets add-on" the option after I performed the previous steps.
I'm not sure. I've also tried to publish an add-on but couldn't figure out what any of it meant. Google Drive and Docs seems to be forever changing the way things work and then only rolling out the features to certain people (to do with geography a/b testing)? It makes it kind of confusing tbh.
(Really neat idea by the way -- looking forward to hopefully bring some of my SQL skills to bear on my accounts.)