You may consider this another possible solution to your issue.

If it is explicitly meant for the Sheets API, then the Google Sheets API does not have a built-in feature that is equivalent to UsedRange. If you'd like to request a feature similar to Excel's Worksheet.UsedRange in Google Sheets, I suggest submitting a feature request through Google’s Issue Tracker. Clearly explain your use case and the benefits of this feature to increase the likelihood of it being considered.

Refer to this documentation for instructions on creating an issue in the Google Issue Tracker.