Hello @Swing Wren. Sorry about the delay coming back to you. The dayjob has been very pressing and the time for GSFU support has been tight.
Im not sure I understand correctly the case. What you mean "importing that data causes to import all the spreadsheet rows"?
Regarding the password, your approach seems fine, however it may be limiting if the project uses any sort of CI/CD, so if you use for example Unity Cloud Build, you'll need to include the pass in the repo. Otherwise is good, just make sure that the file is included in the build. I dont have any particular recomendations, as usually the people involved in the project needs access to the service, and is unlikely to result feasible for the devs to not count with the pass.