I'm not familiar with one-way sync. Basically, I want it so that when I delete something on my local drive, it doesn't get deleted on Google Drive. Deletes on Google Drive nor changes on the Google Drive need to be synced back to local machine. Is that one way sync?
The major use case being, if my hard drive fills up I want to be able to clear up not frequently used files, but still have access to them in Google Drive. Basically what GoodSync does, where you check the "Don’t propagate deletes" feature.
I'm surprised to hear that this is the first time this is requested. I made this feature request to the support line back in May, and Gio from Insync responded with "Thanks for the feedback. I'll let the team know about this feature request :)"