Is there any package that allow to backup (or, more simply, to copy) the files on the usb drive on some cloud destination (for example, google drive) with my account credentials?
tar (or sysupgrade -b) then scp or rsync (or just straight rsync) are typical ways to back up across a network. If you've got an SSH-capable destination, that's a one-transfer process. You could also use a desktop with your preferred cloud-storage provider's app installed as in intermediate stop.
Locally: Use rsync?
Cloud: Not really, most clients use languages such as Rust or Go which aren't "embedded friendly" but there are open source clients/libraries for specific services. Some even work with FUSE which makes them more or less transparent.