Google Drive for mac support what do I need to do?

I get a recurrent message each time I boot-up that informs me that very soon Google will not support Google Drive for macOS unless I load the latest macOS update. Problem is that my iMac will not accept this update because of the hardware specification. Does this mean that I must buy a new iMac if I want to be sure that I can use and share the Google platforms? Is there any alternative being offered by Apple, (apart from iCloud Drive)? Thank you.