I may be misinterpreting the question, but if you just want to copy a file from Excel to Google Sheets you can just upload it with their web interface and it will be automatically converted.
If you need the file to be synchronized, you can use the Google Drive sync client, or save the Excel sheet to OneDrive and use Zapier to synchronize the file.
If, for whatever reason, you need to upload the file programmatically, it will be easier to just automate the user inputs with a program like AutoHotkey than to create a Python program to do this.
If you really need the program in Python (which is after all one of the most useful languages for data processing), you can use xlwings
to read the sheet and the Google Sheets API for output.
Another thing you could do to speed up the file read-in would be to add some simple VBA code to the Excel file to output the entire contents to a format more easily readable by python, or exporting the whole sheet as csv and then using the python csv library to read it in.
Another question is why you need it in Google Sheets format anyway. If you just need the file to be accessible via a link, you could upload the sheet to OneDrive and make it accessible. If you need it to be accessible by other programs over the internet, you could transfer it directly or make the file accessible over FTP.