You can't easily back up an in-progress music project in google drive, in its full editable glory. Essentially, you can put a 1 track .wav file on there... But you can't crack it open and edit it easily at a future date, i.e. remove tracks or mix it.

Orrrr you can do a thing called bouncing stems, which bounces each individual track in the song (sometime 100s for pop stuff) into a bunch of .wav files that can be reassembled into the song. But even that is very annoying because once you save a track as .wav, you can't edit in the same way you could when it was a midi track (with midi, you can keep the same notes in place but quickly toggle between instruments and effects). So then you have to try to export midi tracks as midi files, audio files as .wav, and try to preserve any other grouped effects like reverb and delay...

So ok, let's say you've bounced everything down to these stem tracks... You want them to live in state of minimal quality loss... So they take up insane amounts of room. At that point, yes.. you can save them on drive, but you better be ready to pay for obscene amounts of data.

My long rambling point is, it's much easier to have an external drive that you can just make copies of your project files. It takes a few clicks and your music gets backed up in a format that your music production software can instantly read.