quickest fix if the top of my head would be to stop using google sheets :D

if you only need basic functionality then libreoffice would be a good place to start since it's cross platform and if youre running Windows then there's a portable version that you can bring around on a usb.

I use syncthing myself to sync my documents between all my devices. but there lots of other options around like resilio sync, nextcloud etc there's not really much of a reason to be tied to Google anymore